Posts Tagged ‘BKL 1-piece mount’
New BKL mount adjusts for barrel droop: Part 2
by B.B. Pelletier
It’s been half a year since I did Part 1 of this report. I always meant to do today’s test, but other things seemed to crop up every time I was ready. I did make an excursion in another direction to test BSA’s 2×20 pistol scope using another mount on the Beeman P1 air pistol. Such is the tangled life of the airgun blogger!
New territory!
Today’s report takes me into fresh territory with my Slavia 631 breakbarrel rifle. I had earmarked it as a testbed rifle for testing the accuracy of lead-free pellets a long time ago, but the lack of a scope mount caused me to substitute the Whiscombe rifle at the last minute. You see, the Slavia air rifles all share a common problem when it comes to mounting scopes. They have dovetails that are among the very widest on the market. Most 11mm scope mounts will not expand wide enough to fit the 14mm dovetails (they are still called 11mm, which creates a world of confusion among buyers who try to scope their rifles) that are standard on all Slavia breakbarrels. Even for me — with a drawerful of specialized airgun mounts and prototypes — the Slavia remained a gun I could not scope until this new BKL mount hit the market.
Those dovetail grooves may be called 11mm, but they’re really 14mm apart. And that makes a huge difference. Almost no scope mounts will open that wide. Those three scalloped notches are for a specific type of scope stop that no longer exists in the U.S.
I’ve owned this 631 since back in the 1990s when I was still writing The Airgun Letter. I got it from Compasseco (now owned by Pyramyd Air) for a test and liked it so much I decided to keep it. Over the years, I’ve used it for other tests, such as testing the accuracy and penetration of round lead balls; but these tests were done with open sights. Today, I get to discover for the first time how the rifle shoots when a scope is mounted.
Just fit!
The BKL adjustable mount is a one-piece mount that just fits the length of the scope grooves on the 631. There isn’t a millimeter to spare on either end. As for the width, the fit is much easier, though I did have to spread the clamping rails to get it on the gun. For those who are unfamiliar with BKL mounts, they hold onto the airgun by clamping pressure, alone — there are no mechanical scope stops on any BKL mount. It’s often necessary to spread the mount base a little to get it onto the dovetails of the rifle. BKL has designed an ingenious way of doing this with the base screws applying reverse pressure to spread the base “jaws” just the right amount. It’s easy to do and takes only a minute or two extra. Once the mount is on the gun and the base screws are tightened, you have a scope mount that’s not going to move under recoil, no matter how severe.
Droop-compensating!
The second great thing about this new mount is that the rear scope ring elevates to compensate for barrel droop. Newer readers may wonder what droop is, so allow me to explain
The BKL is mounted on my Slavia 631 rifle. The mount is silver because it’s an unfinished preproduction model, not because it’s finished that way.
Barrel droop
Breakbarrel springers are notorious for having barrels that are angled downward from the sight plane. Because the manufacturers mount both the front and rear sight on the barrel, they remain in a fixed relationship that masks the droop or downward slant of the barrel. When you install a scope, it goes on the spring tube and the barrel droop becomes painfully obvious. You adjust the scope up as far as it will go to bring the strike of the round back up to the intersection of the crosshairs. Sometimes, you just barely get there, but other times you can’t even get that high before running out of adjustment. Either way, when a scope is adjusted all the way up as high as it will go, the internal springs relax and the point of aim starts moving all over the place. New shooters blame this on scope shift, but it’s really a different problem that’s completely correctable
You want to mount the scope in such a way that its vertical adjustment is about in the middle of the range or even closer to the low end. That’s where the droop-compensation scope mount, or “drooper” as it’s called, comes into play. With a droop-compensation scope mount you can slant the scope downward so it follows the line of the bore more closely.
And this new BKL is a drooper mount! But until I tried to sight in my Slavia 631, I had no way of knowing that it’s a breakbarrel with a droop problem. Once I confirmed that it is, I adjusted the rear of the BKL mount upward and got the scope dead-on at 25 yards! It took only one adjustment, and I had the scope back into the middle of its adjustment range again. Now, it was time to see how this rifle shot.
Twitchy
This is going to be a longer report, so I’m cutting to the chase right away. When I started shooting the 631 at 25 yards, I discovered that this rifle is twitchy. What does that mean? Well, if a breakbarrel is very powerful, it’s usually extremely difficult to hold for accuracy. It wants to spray its pellets all over the place — that’s what I call twitchy.
But lower-powered breakbarrel springers like this 631 aren’t usually twitchy. Usually, they lob all their shots to the same place. They’re also very tolerant of different types of pellets. But my Slavia 631 is none of those things. It’s twitchy. Allow me to show you what I mean. The first group I tried to shoot was with the Air Arms Falcon pellet.
This first target shot with Falcon pellets revealed a lot about the gun. Do you see that two pellets are close together in each of the three groups, but the point of impact moves? That’s due to very small changes in the hold. Four of the 10 pellets missed the target altogether!
The first group I attempted told me this rifle is twitchy. But sometimes that’s only with a couple pellets, so I pressed on.
Next, I tried shooting RWS Hobby pellets. They did better and were less twitchy but were not really that good.
Ten Hobbys went into a real group at 25 yards. It looks like only 6 shots landed because several went through the same holes. This is a better group, measuring 0.73 inches between centers, but it’s still not great.
I had to use every bit of technique, short of a scope level, to get that group. The differing points of impact were obviously the result of very subtle changes in the hold. This was obvious to me as I shot, because I was able to feel where the pellets wanted to go. But in spite of that, I did my best to shoot the tightest group I could.
I tried Crosman Premier lites next, but they were all over the place. Then, I tried the JSB Exact RS pellet that often proves best in rifles of this power level. This time, though, they were too hold-sensitive to do well.
Finally, I tried the BSA Wolverine pellet that’s also a medium weight JSB but is subtly different from the others of the same weight (8.44 grains). Like the Hobbys, I got a group of 10; but like the others, it’s interesting for being more of a cluster of several smaller groups.
Ten BSA Wolverine pellets gave this group, which measures 0.75 inches across. There’s a cluster of 6 in one hole, then 4 others below. The fourth shot lies between the two that are stacked vertically.
Bottom line
The BKL adjustable scope mount works as advertised. It’s easy to install and to adjust. And it has jaws that are wide enough for the widest 11mm air rifle dovetails. Just don’t try to use it on a Weaver base, because it isn’t that wide, nor is it configured for the proprietary shape of a Weaver dovetail. This mount is one elegant solution for a drooper.
The Slavia 631 is a twitchy breakbarrel that shoots at a mild level of power. If I hadn’t done this test, I never would have guessed that from the muzzle velocity, alone. That made me think of another report I can write — and probably should: What to do with a twitchy breakbarrel. It would be a collection of the tricks and techniques I would use when I encounter a twitchy breakbarrel. In my role as an airgun tester, I see a lot of them over time, so I’ve built up a bag of techniques I employ to deal with them when one comes along.
The 631 is also a great potential testbed for an adjustable muzzle weight to be used for tuning the harmonics of a spring gun. I’ll look into that.
TalonP PCP air pistol from AirForce: Part 6
by B.B. Pelletier
Part 1
Part 2
Part 3
Part 4
Part 5
TalonP air pistol from AirForce is a powerful, new .25-caliber pneumatic hunter.
It was another calm day at the range last week when I tested the TalonP air pistol once again. This time, I had a couple special goals. One was to see if the new method of scope mounting recommended by AirForce owner, John McCaslin, would help me hold the gun better, and the other was to test the velocity of the gun with the most accurate pellets on power setting eight.
New scope mounting method
The scope has to be moved forward for increased cheek contact with the reservoir/tank. You know that I’m now using the optional shoulder stock extension that clamps onto the pistol’s reservoir. The way it clamps gives you a wide range of pull lengths. I need a longer length of 14.5 to 14.75 inches, so I have the extension way out at the back of the reservoir, but most shooters will slide it in a bit. John recommends that you adjust the stock first then position the scope where it needs to be for your eye. He recommended a BKL cantilever mount that pushes the scope forward. I used their BKL 4-inch one-piece mount with what they refer to as drop compensation, which actually means droop. Because the one I had on hand has one-inch rings, I had to say goodbye to the superb Hawke 4-14×42AO Sidewinder Tactical scope I’ve been using and substitute a Leapers 5th Gen 6-24×50AO scope. While it was entirely adequate, I have to observe that the Hawke at 14x was clearer than the Leapers at 24x.
The first time around, the Hawke scope was mounted on two-piece BKL mounts that were slid as far forward as possible. The image was still too close to my eye to resolve to full size, so I needed to move the eyepiece of the scope forward about another half-inch.
Using the BKL cantilever mount I was easily able to move the scope slightly forward to allow my cheek to rest comfortably on the reservoir when I sighted. As you can see, there’s still a lot of room.
With the cantilever mount moving the scope forward, the eyepiece was positioned perfectly for a good cheek weld on the reservoir. The ear protectors are for the firearms that are next to me.
Sight-in took longer because, at this rifle range, I don’t have the ability to place a small target at 10 feet. I have to mount all my targets at the 50-yard backstop. So, I mount a two-foot by four-foot silhouette target on the backstop with its plain, light backside facing me. Then, I place the sight-in target in the center of that, and usually I can catch the pellet holes somewhere on that huge piece of paper. You could use cheaper paper for this — just as long as it shows the pellet holes clearly. I’ve never used a scope collimator, and I don’t intend to start now. This is so much easier!
I hadn’t changed the power setting from the last test, so the performance went the same as before; this time, I cut off the fill at less than 2,700 psi. That allowed me to start shooting a group in three shots. As I learn this pistol, I’ll eventually learn exactly where to stop the fill so shot one is right on the money every time. However, as with most airguns — including springers — you have to “wake” the gun with a couple shots each new time. For hunters who spend hours between shots, this can be daunting; but very few guns will put the first shot in the same place as the others after a long period of rest. It’s true of firearms, as well, so I guess it should also apply to airguns.
How did it do?
Nothing really changed from the last time I tested this pistol. Now that I have the air fill down pretty well, I can even do “tricks” with the gun. Let me demonstrate with JSB Exact Kings and Benjamin domes.
50 yards: Five JSB Exact Kings in the hole below and two above. The five-shot group was 0.246 inches between centers. Add the other two shots, and the group grows to 0.577 inches between centers. Even that is better than most .25-caliber air rifles can do at 50 yards; but the point (trick) is that I knew those last two shots were going to stray, and I didn’t have to shoot them.
50 yards: Five Benjamin domes in the hole on the right and then I shot a sixth that I guessed would stray. Stray it did, but to the left this time, where in the last test Benjamins moved to the right. Go figure! The tight group measures 0.38 inches. With shot six, it opens to 1.059 inches.
Technique is important!
Lest a new airgunner buy this airgun and splurge on all the support equipment to operate it (basically just a carbon fiber air tank), and then buy the same exact pellets I’ve used in this test, only to be disappointed that he cannot replicate what I’ve done, allow me to show you how I’m able to do what I’m doing. It’s not a trick, but it does require an advanced shooting technique of which a new shooter is probably not aware. You will remember that I mentioned my intention to mount a scope level on the gun last time. I forgot to do that, but on a printed target there are plenty of references to help me control the amount of cant (the amount the rifle is tilted to one side) for every shot. So, for the two groups I’ve shown you thus far, I watched the visual cues as precisely as I’ve been watching the bubble level in the Pellet velocity versus accuracy test. Let me show you what it looks like when I ignore these cues and just shoot when I think the airgun is being held the same every time. I’m trying just as hard to shoot a good group, except I’m ignoring the one variable of cant.
50 yards: This is what you get when you don’t pay attention to cant when shooting an accurate pellet at 50 yards. Five JSB Exact King pellets made this 0.747-inch group. That’s still a very good group for a .25-caliber airgun at 50 yards, but it looks large in comparison to what I’ve shown you previously in this report.
Velocity
I tested the velocity of this pistol with several pellets back in Part 2. That was when we confirmed that the TalonP isn’t just capable of hitting 50 foot-pounds at the muzzle — it can actually shoot a string of 10 shots above that energy figure.
Today, I’ll give you the velocities of the two most accurate pellets. I’m doing this for one reason. The 43.2-grain pointed Eun Jin pellets that are required to achieve that bragging power are not the most accurate pellets in this airgun. The two I’m showing today are, and they’re best at power setting eight. This is a real-world look at what the pistol can pump out when it can also keep five pellets inside a wedding ring at 50 yards.
JSB Exact Kings
The gun was filled to 2,700 psi and shot over an Oehler chronograph. The average velocity of JSB Exact Kings for the five best shots was 875 f.p.s., with a low of 860 and a high of 892 f.p.s. At the average velocity, the muzzle energy is 41.66 foot-pounds. So the total spread of velocity for the pellet that would put five under a quarter-inch at 50 yards was 32 f.p.s., but you can see that it doesn’t really matter that much.
If I had included the very first shot fired after the fill, the velocity was 844 f.p.s. and the next shot was even slower, at 836 f.p.s. I got a total of 11 shots on a fill, the last of which went 841 f.p.s. I’ve shown you both last time and today that there are five screaming shots within this larger string that I know for certain will be accurate if I do everything right. Do you want to kill the woodchuck at 60 yards, or do you just want him to envy you?
Benjamin domes
I refilled the gun to 2,700 psi and shot a string of Benjamin domes. They averaged 877 f.p.s. with a low of 840 and a high of 902 f.p.s. That’s a 62 f.p.s. spread, yet you can see what they did on target. This pellet generates 47.49 foot-pounds at the average velocity. Looking at the total string, shot one went 783 f.p.s., and shot 11 went 827 f.p.s. Those shots are outside the string that gives the best accuracy, and you’ll break your heart by hoping to get them to go into that tiny little group. Take your five great shots, or think about buying a different pellet gun.
You won’t find another pellet pistol that will touch this one for power and accuracy at this range, and many pellet rifles will fall behind as well. The TalonP air pistol is not for everyone. It’s for the shooter who has the heart of a buffalo hunter. The one who knows exactly what his gun is capable of and is willing to invest the time and care to get it.
Airgun hunter, Eric Henderson, has already taken a prairie dog at 100 yards with the exact same pistol I’m testing for you. I’m not the only one getting these great results.
What I’ve done is take the time to decode the operation of the gun and find two good pellets for it. I’ve told you the best fill pressure, which is way less than what the factory recommends. I’ve given you the power setting, which is under the maximum setting.
The TalonP is a thinking shooter’s airgun. If you want the most accurate and most powerful smallbore air pistol in production today, here it is.
Gamo’s Silent Stalker Whisper IGT air rifle: Part 4
by B.B. Pelletier
Gamo Silent Stalker Whisper IGT surprised B.B. by being difficult to group.
Before I start today’s report I have to share a concern. The other evening while we were watching TV, Edith suddenly suggested that I write an airgun blog for beginners. I thought about it, and I decided she is probably right.
Of course, this very blog is supposed to be for beginners, but I fear that I’ve wandered away from that objective. There’s too much jargon in the articles and not enough explanation. As far as the comments are concerned, I have no problems with what’s said because readers ought to be able to say almost anything. But the articles ought to be more informative and not require an airgun background to understand.
If you’re new to airgunning and have been struggling with this blog, please speak up now. I would like to hear your views on how we can make this blog better and easier to understand.
Okay, on to today’s report, which, if subtitled, would read, BB gets frustrated. I’ve tried to like this Gamo Silent Stalker Whisper IGT. I really have, and I did like many things about it. I liked the light weight, the ease of cocking and the lack of vibration when fired. I didn’t care for the scope Gamo sends with the rifle, but today was supposed to take care of that. But it didn’t work out that way. Instead, adding a better scope only demonstrated that this rifle isn’t going to shoot like it should, and I believe I now know why.
New scope
You’ll recall that I criticized the Gamo scope pretty severely, so for today’s session I mounted a Leapers 6-24×50 AO scope in the BKL 1-piece droop compensating mount I’m using to compensate for the rifle’s extreme droop. Blog reader Kevin has said that he wouldn’t buy another Leapers scope because of the way he was treated by the company in what should have been a warranty situation, and I have to agree with him on that; but their scopes are still a very good value for the money. This scope is one I’ve used several times before, and it’s never let me down.
I figured the first thing to do was to verify my zero after changing out the scope, and of course there was a lot of adjustment to be made with the new one. I have no idea what gun or mounts this scope was associated with last, so it will naturally be off unless I get lucky. But this wasn’t the day for luck.
After zeroing, the first pellet I tried was the 14.3-grain JSB Exact Express that looked so tantalizing in the last accuracy test. And this is where the frustration began. In the last test using the poor scope, I managed a 10-shot group that measured 1.267 inches between centers. I expected far better than that, now that I could clearly see the target. But after only seven pellets went into a group measuring 1.479 inches, I knew it was not to be.
JSB Exact Express pellets spread out so far that I gave up after seven shots.
I then changed to the heavier 15.9-grain JSB Exact Jumbo pellet. But another seven of those pellets went into a group measuring 1.427 inches, and I stopped wasting my time.
JSB Exact Jumbos weren’t much better, with seven going into 1.427 inches. I didn’t complete this group, either.
I was really frustrated, because nothing I tried was working. I would get two pellets in the same hole when I tried a new hold, and then the third would land two inches away. This was starting to get embarrassing! And I did try many other pellets, including some that are obsolete, like Beeman Silver Jets. Nothing worked. RWS Hobbys were so far off-target that they put a hole in the aluminum light fixture I use to illuminate the target. And Beeman Kodiaks, which I think are much too heavy for an air rifle in this power class, were doing the same thing as all the rest — grouping two tight and then throwing the next two several inches away. Then I shot another disappointing group of H&N Trophy Hunters.
Finally in desperation I shot a last group of Beeman Silver Bear hollowpoints that ended with the fourth shot. Why shoot any more when four shots already has you over one inch? Look at the group, and you’ll see what I mean.
When a group begins like this, why bother going farther? Four Beeman Silver Bears at 25 yards.
Now this is the point in many reports where I pull back the curtain and reveal the sunshine of a successful test. But not today. There is no joy in Mudville today. Oh, that’s not true.
I felt so bad about all the lousy shooting, and believe me, there’s more than I’m reporting, that I grabbed my tuned .177-caliber Beeman R8 and shot a final group of ten Beeman Devastators at the same 25 yards. This was to wash the bad taste of this test out of my mouth.
This group of ten Devastators came from my Beeman R8 at 25 yards. The group measure 0.5 inches on the nose, allowing for the built-in error.
And it worked. Apparently I can still shoot — even on a day when I can’t get the Gamo Silent Stalker Whisper IGT to shoot worth a darn. It just felt good to be able to say that.
So, what’s wrong?
I think I know why the Silent Stalker Whisper isn’t grouping, and there isn’t a darn thing I can do about it. Early on in this second accuracy test, I started grabbing and shaking things to see if anything was loose. When I came to the barrel, it shook from side to side. It wobbles on its pivot, and there isn’t anything I can do about it.
I see from examining the action outside the stock that a lot of thought went into this gun, but they missed a very critical point — the barrel lockup. If that’s loose and can’t be tightened, and apparently it can’t, then the rifle will never live up to its potential. It’s still a nice lightweight breakbarrel with smooth shooting characteristics, but it lacks the all-important accuracy potential shooters want.
Tech Force TF99 Premier air rifle: Part 3
by B.B. Pelletier
The Tech Force TF99 Premier underlever air rifle is a large, powerful spring gun. This model has evolved a lot over the years.
Before we begin today’s report, I have a special sale to announce. Pyramyd Air has a super special deal on two spring air rifles.
The RWS Diana 350 Magnum in .177 with the T05 trigger was $399 and has been reduced to $299.95. This is the T05 trigger model that we discovered works just as well as the newer T06 trigger. The Hammerli Pneuma in .177 was $349 and is now $299.95. Here’s your chance to get a fine PCP for $300!
Today, we’ll look at the accuracy of the Tech Force TF99 Premier underlever air rifle. Some assumptions I made in Part 2 have to be changed after today’s test, but I’ll get to that.
Short scope dovetail
For starters, the TF99 has a very short dovetail for the scope mount, so one-piece mounts are mostly too long. I had to use a two-piece BKL one-inch, double-strap, high-profile ring set to mount the Leapers 3-9×50AO scope. The high mount gave me good clearance for the 50mm objective, but I had to hold my head higher on the comb to see the image in the scope.
Cleaned the barrel before shooting
I decided to go ahead and clean the barrel before testing with J-B Non-Embedding Bore Cleaning Compound on a brass brush run through the bore 20 times in both directions. Since this rifle has a sliding compression chamber, I had to enter the barrel at the muzzle. I put a cleaning patch over the air transfer port hole when the breech was slid back to prevent any dirt or cleaning compound from entering the compression chamber. The bore was loose and did not resist the brush like most new barrels do, so this bore is on the large side of normal.
Sight-in
I then sighted-in the rifle at 10 feet, prior to backing up to 25 yards. I used my special 10-minute sight-in procedure that works so well.
Some difficulties encountered
The rifle I’m testing has a lot of barrel droop, but the scope mount is not set up to compensate for it. Rather than spending another hour to re-do what I’d already finished to get to this point, I used a writer’s trick that works very well. The next time you think you have a scope problem, try doing this.
My groups were spread out laterally, and in a couple cases were falling into two distinct groups. That’s a classic sign of a weak erector tube spring, the cure for which is to adjust the scope’s elevation downward. So, I adjusted the elevation knob down 40 clicks and the lateral spread went away. Of course, my groups are nowhere near the point of aim. Since this test is just to determine the relative accuracy of the rifle, all I care about is how tight the groups are — not where they land. If I were going to shoot this rifle at targets, I would have to mount a drooper scope ring set to compensate for the droop so the scope could be adjusted normally.
Another difficulty I had was discovering how to hold the rifle. I tried it several ways with the off hand back by the triggerguard, but the TF99 doesn’t seem to want to be held that way. Then, I slid the flat of my palm out to the beginning of the cocking slot and that was where the rifle shot best. I remember when Mac tested the Browning Gold a few weeks ago that he found the same thing. Sometimes, you just need to play with the rifle until you discover its secrets.
Pellets tested
I tested a lot of different pellets while learning the secrets of this rifle, and I shot 10-shot groups with each pellet at least one time. With several of the pellets, I shot more than one group. Rather than show a bunch of large groups that were used to diagnose how the rifle likes to be held, here are the pellets I tested:
Beeman Kodiak
Crosman Premier 7.9-grain dome
RWS Superdome
Air Arms Diabolo Field dome 8.4 grains (JSB Exact)
RWS Hobby
Air Arms Falcon dome
Right off the bat, I’ll tell you that the RWS Hobbys are not the right pellet for this rifle. All other pellets tested seemed to group about the same, and the Beeman Kodiaks were the best of all I tested. But even with all the techniques and tricks, the TF99 is not a tackdriver. It’s capable of producing about a one-inch, 10-shot group at 25 yards under the best conditions. And, only Beeman Kodiaks were able to do that. The others seemed to group into 1-1/8-inch groups or slightly larger at the same distance.
Ten Beeman Kodiaks made this group that’s 0.946 inches between centers at 25 yards. The aim point was at the top of the target, about four inches above the impact point because the scope was adjusted down to eliminate erector tube bounce.
Velocity
I said I would retest velocity after the accuracy test because the rifle was dieseling during the initial velocity testing. Well, the dieseling continues after this test as well, and the 7.9-grain Crosman Premiers that averaged 956 f.p.s. in the first test now average 961 f.p.s. The spread went from a low of 951 to a high of 965 f.p.s., so the rifle hasn’t changed much even after 100 more shots have been fired. I think this is a rifle that needs a 1,000-shot break-in.
Firing behavior
The rifle has low recoil for its power, but it vibrates more than a little. I got used to a buzz after each shot.
The flat underside of the stock allows this rifle to lay very well on your off hand. It felt very neutral during accuracy testing, once the correct balance point was found.
The trigger is a single-stage and surprisingly crisp, though very heavy at the same time. I didn’t appreciate how it felt during velocity testing, but it came through loud and clear in this test. It’s a bit too heavy for the absolute best work, though I don’t think it cost me more than 1/8 inch in any of the better groups.
General impressions
The bottom line is that the TF99 underlever is a well-made, powerful underlever with reasonable accuracy if you do your part. It certainly isn’t a tackdriver, but it’ll hit a walnut or a cookie at 25 yards every time when the right pellet is used.
The right pellet, among those I tested, turned out to be the heavy Beeman Kodiak that I said I would not use in part 2. I said that because a spring-piston airgun generally likes medium and lightweight pellets best, but that was what I got wrong. This rifle likes the heavy pellets best, and it only came out when it was shot for accuracy.
New BKL mount adjusts for barrel droop: Part 1
by B.B. Pelletier
Announcement: Due to a mix-up, the most recent Big Shot of the Week winner wasn’t announced last Friday. Jeffrey Aaron Demers is this week’s winner of Pyramyd Air’s Big Shot of the Week on their facebook page. He’ll receive a $50 Pyramyd Air gift card.
Jeffrey Aaron Demers is this week’s Big Shot of the Week. Congratulations!
The optional BKL bubble level is mounted on the left side of the new BKL adjustable scope mount. This view shows the rear of the mount raised up to compensate for this rifle’s barrel droop.
Today, I’m going to show you the new BKL adjustable scope mount that will soon be available. I mentioned this mount in the Part 3 test of the new RWS Diana T06 trigger last week, which is where the first picture comes from. I’ll show all the nuances of the new mount and discuss how it works.
Looking up from the underside of the mount’s rear ring, we see the two legs that slide up and down for elevation compensation. Note that the ring has two cap screws.
The front ring is captured, so all it can do is rotate as the rear ring goes up or down. This prevents stress on the scope tube.
These first two detail shots show how the mount works. The rear ring moves up and down on forked legs that are open on the bottom. Two screws on the sides of the legs jam the ring tight in position when the right elevation is achieved.
The front ring is captive and is only able to rotate when the rear ring moves up and down. This prevents stress on the scope tube.
The black elevation pad is a Delrin screw that the scope tube rests on. It’s located just ahead of the rear ring.
Another key feature of this mount is the elevation pad, located back by the rear ring. The scope tube rests on this pad, which is used to make very small adjustments to the elevation of the scope. A small Allen wrench inserted into one of the holes in the periphery of the elevation pad lets you turn it up or down like a capstan, providing tight control over the elevation changes made. When the scope rests on the pad, it provides additional support against random movement once the scope ring screws are properly locked down.
Does it work?
I tested this mount on an RWS Diana 34P that I’ve retained for tests just like this. The rifle in question has 21 inches of droop at 20 yards (the only sight-in distance I use, since the pellet strikes the same place as the 30-yard point of intersection when it crosses the line of sight for the second time), making it a severe case of barrel droop. When I developed the UTG droop-compensated scope bases for RWS Diana spring rifles, this rifle was the worst test case, against which the base for the RWS Diana 34 base was designed. If the BKL mount can fix the droop on this rifle, it can fix anything you’re ever likely to encounter.
And fix it, it did! With the mount adjusted about as far up as it could go and still be locked in position, the scope was sighted-in dead-on at 25 yards, which is in the center of the 20-30 yard sight-in distance. And, the scope was in the center of its click-adjustment range. This was an acid test that the BKL mount passed with flying colors.
Another factor I was watching was the BKL mount’s ability to hold its position on a heavy-recoilling spring rifle. When the mount was given to me for testing, it had already withstood the jackhammer recoil of a Hatsan 125, which is even harder on scopes and mounts than the UK-produced Webley Patriot. Indeed, the scope that had been in that test was destroyed, but this mount held fast.
On the RWS Diana 34P, the mount also held fast under two different scopes, the intial one that finally gave up the ghost during my test and the replacement scope. Hundreds of test shots were fired without a hint of scope mount movement or scope movement in the rings. Despite there being just two screws per scope cap, both scopes remained in place throughout the test.
Additional features
This mount also offers 11mm dovetails on both sides of its base. If you want to attach a laser, tactical flashlight or rangefinder, your base for them is built right into the scope mount. Because BKL recesses the Allen screw heads into the base, both sides of the scope base have this feature and can be used in this way.
Here you can see one of the two 11mm dovetails in the base of the BKL mount. There’s another one on the other side, and recessed screw heads make it accessible for this purpose, as well.
The final feature this scope mount offers is the facility to mount a bubble level to the base of the new mount. It attaches to one of the three spreader holes in the base, though I think you’ll choose the hole that’s farthest from your eye so you can focus on the bubble. I used this level in the test of the RWS Diana 34P, and it worked well.
An optional BKL scope level can be screwed into one of the three spreader holes (the center hole in each group of three) on the base of the new BKL scope mount.
Mounting
If you need to spread the base of the mount to get it on a gun, the ring screws also have to be loosened. Then, the base can be spread evenly by the three spreader screws.
The best part
I’ve saved the best for last. When this mount was shown to me at the BKL factory, I was told that the motivation for making it the way they did wasn’t an air rifle, but a popular air pistol! The cuts on the mount are specific to clear the front sight on the Beeman P1/HW 45 spring air pistol.
The profile of the new BKL adjustable rings was made to accommodate (to clear) the front sight of the Beeman P1 pistol.
The Beeman P1 was the inspiration for the new BKL adjustable scope mount.
Because this is the first mount I’ve seen that was made for the P1, I think I’ll order a BSA pistol scope and give it a test. Whatever scope you select has to fit into the two rings that measure 4.0625 inches apart on the outside. Because this is a one-piece scope mount, those rings cannot be moved, so pick your scopes accordingly.
Comparing the T05 trigger to the T06: Part 3
by B.B. Pelletier
RWS Diana 34 Panther
Part 1
Part 2
Part 3
Part 4
Pro-Guide spring retainer system for RWS Diana rifles — Part 5 The RWS Diana 34 Panther
Part 5
I’m testing the T06 trigger today using the accuracy test as a means to evaluate the operation of the trigger. The object is not to see how accurate this RWS Diana model 34P is. We already know that from tests run long ago. But as I try to shoot groups with the gun, I can get the feel of the new trigger better than any other method. So, today is about a trigger and not about this air rifle.
Of course, I’ve already used the trigger a lot in the velocity testing I did a couple days ago. Now, however, I’ll be holding tight on a small target, and any aberration in the trigger will come though loud and clear. This is where the rubber meets the road!
New BKL adjustable mount
I’m also testing the new BKL adjustable scope mount at the same time, and the next report will be exclusively about that. I showed you the new mount in Part 1, but what I didn’t show you was the bubble level that’s attached to the left side of the mount base.
The optional BKL bubble level is mounted on the left side of the new BKL adjustable scope mount. This view shows the rear of the mount raised up to compensate for this rifle’s barrel droop.
With this level attached, I can sight with one eye and watch the bubble with the other. I can’t see both at the same time, which is why a scope with an internal bubble level would be so desirable, but at least I don’t have to move my head to see the bubble like you do with some other levels. I’ll be reporting on it when I cover the mount in the next report.
Back to the accuracy test
I learned in the past that this rifle really likes 7.9-grain Crosman Premiers, so instead of fooling around with many different pellets, I selected just these pellets for the test. That way I could forget about trying to make the rifle shoot well and concentrate on the trigger.
Ten Crosman Premier lites went into this 0.443-inch group at 25 yards. It’s a little larger than Roosevelt’s head on the dime but smaller than the entire coin.
Though I’m only showing you a single 10-shot group, I shot much more than that. I probably shot 50 shots for today’s test, on top of about 20 the day before when I was checking out and adjusting the new mount. With all this testing, I became very familiar with the T06 trigger.
How the T06 trigger differs from the T05
The T06 operates differently than the T05 did. The T05 stopped cleanly at stage two and held there until the instant the sear released. There was no feeling of movement once stage two was engaged.
The T06 also stops cleanly at stage two, but as you continue to pull you can feel the trigger moving through the stage. Normally this is called creep, but it is absolutely smooth with no pauses or hesitations, and it doesn’t fit the popular definition for trigger creep. In fact, this movement becomes entirely predictable and something a shooter can learn to live with.
Something else about the stage-two pull on the T06 — on most triggers, when you pause part way through stage two, back off and then return to it again, as much of it that was pulled through is still gone. You’ve advanced the trigger or shortened the stage-two pull, whichever you prefer. Not so on the T06.
Because the Diana 34P requires so much technique (the artillery hold) to shoot accurately, I found myself stopping several times before the trigger released to take another breath. When I did that, naturally I relaxed my trigger finger as well. Then, I had to settle myself again before returning to the trigger. What I found when I got back on the trigger was that it had reset itself to the start point. The full trigger-pull was restored. This is what I want all triggers to do, because anything else means an unpredictable trigger that could release before I’m ready. From that standpoint, the T06 is a very nice trigger. The T05 didn’t have the problem of pulling part way through stage two, so of course it always acted like it had just been set whenever you came back to it as well.
The bottom line
Diana has made a change with the T06 trigger. In my observation, it isn’t any better or worse than the T05; it’s just different. If you want a metal trigger blade, the T06 has it. If you want adjustments, the T06 has more of them. I wasn’t able to eliminate the travel in stage two, but that doesn’t mean it can’t be done. I spent all of 30 minutes adjusting the unit. Someone who is willing to put in more time can probably discover secrets that I didn’t find.
The bottom line as far as I see it is the T06 trigger is now here and the T05 is a thing of the past. I alerted you to the difference between the T05 and T06 pistons, so you know they go together and a T01 trigger can also use the same piston as the T05.
The new trigger is nice and predictable. It has the features I’ve mentioned, and they all work well. If you wind up with one on your next Diana airgun you should be satisfied with it. But if you currently own a T01 or a T05 trigger, I wouldn’t plan to change it.
Comparing the T05 trigger to the T06: Part 2
by B.B. Pelletier
RWS Diana 34 Panther
Part 1
Part 2
Part 3
Part 4
Pro-Guide spring retainer system for RWS Diana rifles — Part 5 The RWS Diana 34 Panther
Part 5
You’ll notice that I’m doing something different in today’s report on the RWS Diana model 34P T06 trigger. I linked not only to Part 1 of the T05/T06 trigger report, but also to the entire RWS Diana 34P report (it used be called the 34 Panther) that was done way back in 2007. I did that because in changing the rifle to the new T06 trigger, I also had to replace the piston. (In Part 1, I mentioned that the T06 trigger requires a different piston to work.)
I also linked to the report where I installed and tested the Air Venturi RWS Diana Pro Guide spring retainer system in this rifle. That single link takes you to the fifth report in an entire series on just the Pro Guide, and that tune is still in this test rifle.
On to today’s report
When I removed the old piston from the rifle for the new trigger installation, I saw that the edge of the seal had been chipped in a couple places, which might have had an effect on the old velocity figures. Although the mainspring remains the same (it’s that Air Venturi Pro Guide upgrade kit I told you about) for both pistons, I have no way of knowing if the piston seal was damaged when I did the velocity test before, so I’m doing the test, again, today.
Here you can see the main cut near the top of the piston seal and a smaller one at the 3 o’clock position. What looks like a third nick on the other side of the seal is just some excess material sloughing off. Although these are very small imperfections, they might have caused some loss of velocity.
You saw the T06 trigger adjustments in the last report. Here’s what the T05 trigger looks like.
The T05 trigger and piston shown together. Compare them to the same picture of the T06 trigger and piston in the last report.
Some of the more anal among you may wonder whether the new seal made it into the gun okay this time, or am I faced with yet another damaged seal. Well, knowing what happened last time I was very careful to tuck in the new seal past all sharp edges of the mainspring tube as the piston slid in, which is usually where such damage happens. I feel reasonably certain that the new seal isn’t damaged. If testing proves otherwise, I’ll pull the piston and examine the seal.
Something new
Another reason I’m doing the test this way is because of a new BKL product. Last week, I told blog reader Kevin about a new BKL adjustable low mount, and now I’m going to show it to everyone. The mount I’m using here is a prototype, but the production mounts are very close to being completed and shipped and should be available for sale in less than two months.
This new mount is adjustable for height, so it’s an anti-droop mount. And, this RWS Diana 34P is the very gun I used to test the original Leapers UTG Diana drooper mounts. This is the rifle that shoots 21 inches low at 20 yards (that’s 6 inches low at 35 yards with the elevation cranked up as far as it will go)! What better gun on which to test an anti-droop mount than the very one that droops the most of any I’ve tested?
The new BKL adjustable mount is lower than most adjustables, yet it allows a 50mm objective to clear the spring tube when full droop is applied. The black post at the rear of the mount controls the vertical adjustment. This mount is a prototype that hasn’t been anodized black.
I’m not going to cover the mount today, but I’ll do a special report on it after the accuracy testing is completed. Remember, folks, what we’re really looking at in this series is the performance of the new Diana T06 trigger. But time and circumstances have allowed us to also look at some additional things as we do.
Today’s report
We’re going to establish the velocity of the rifle with the new piston and seal. I didn’t expect to have any velocity change from the old piston until I saw that seal. As I report the findings, I’ll remind you of the velocities obtained with the same pellets back in 2008 in Part 5 of the Pro Guide test (after it had been installed in this rifle).
Crosman Premier lite
The first pellet I tested was the venerable Crosman Premier 7.9-grain domed pellet. This pellet proved to be quite accurate in this rifle, and I expect it to continue to be accurate in this test. In the original model 34, as it came from the factory, this Premier pellet averaged 919 f.p.s. After the Pro Guide was installed in 2008 in the gun with the T05 trigger, the average velocity increased to 936 f.p.s. When I tested it this time, the average was 956 f.p.s. The spread went from 937 all the way up to 971 f.p.s., so the gun is getting used to its new situation, but that’s still a small increase.
RWS Hobby
The next pellet I tried was the RWS Hobby. In the factory 34, Hobbys gave me an average of 1021 f.p.s. After the 2008 installation of the Pro Guide system, the average was still 1021 f.p.s. With the latest T06 trigger installation, the average is still 1021 f.p.s. Apparently, that’s a speed this rifle likes for Hobbys. The spread this time went from 1011 to 1031 f.p.s., so just 20 f.p.s. That’s pretty consistent for a springer.
H&N Baracuda Match
The last pellet tested was the H&N Baracuda Match. These pellets underwent a weight change over the past two years; although they became lighter, they still registered lower velocity with the latest tune. In factory trim, they averaged 820 f.p.s.; after the Pro Guide was installed, that increased to 825 f.p.s. With the latest tune, they now average 801 f.p.s., with a spread from 795 to 808 f.p.s. That’s a very tight 13 foot-second spread; but as you can see, the average has fallen. I do believe this is a different pellet than the one I used before even though the name is the same, but there’s no way to prove it and it doesn’t matter anyway. The current pellet is all you can buy, so it is what it is.
Based on the results of this test, which I verified with additional shots after the chronographing was completed, I proved that the gun was shooting as well as could be expected when the T05 trigger was installed. The cuts on the piston seal appear to have made no difference. There has been almost no change with the new installation.
The T06 trigger
My initial impressions of the T06 trigger is that it is a fine sporting trigger, but it offers no substantial improvements over the T05. This trigger has some creep in the second stage that I’ll try to adjust out. The T05 had zero creep. Its pull can be adjusted lighter than the T05 pull, but it’s somewhat creepy, which more than offsets the lighter breaking weight.
The real test of a trigger comes when you’re trying to shoot for accuracy, so I’ll reserve final comment until then. After the accuracy test, I plan a special report on the new BKL adjustable low mount to show you all the features. By that time, I’ll have hundreds of shots on the gun with the scope mounted, which will serve as a test of it’s stability. And, there’s more…but you’ll just have to wait.
