Posts Tagged ‘cleaning’
Five things you don’t want to do to your airgun
by Tom Gaylord, a.k.a. B.B. Pelletier
This blog is for those who are new to shooting and to airguns. Sometimes, we have to address the basics, and that’s what I’m going to do today. I’m inviting the veteran shooters to chime in with their own ideas of what the new airgunner should avoid.
1. Over-cleaning
For reasons I cannot fathom, new shooters think they need to clean their airguns even more than firearms are cleaned. I know people who never clean their .22 rimfires until they start to malfunction, yet these same people don’t hesitate to take a bore brush to the barrel of their favorite air rifle every chance they get. It isn’t necessary to clean an airgun barrel that often, and it actually exposes it to possible damage from the cleaning process gone wrong.
Why do we clean a gun?
Historically, guns used what we now call black powder, whose residue both attracts moisture and then turns it into sulphuric acid. It begins to do this in less than 24 hours following shooting, so cleaning was/is essential if the bore was to be preserved. Later, when smokeless powders were developed, the early primers that ignited them contained compounds that were just as corrosive to the bore as black powder residue. A great many .22 rimfire rifles have lost all their rifling from the combined activities of this primer-based corrosion, coupled with over-zealous cleaning.
More recently, shooters have discovered that the jacketed bullets of centerfire cartridges will quickly foul barrels with metal deposits. While this doesn’t corrode the metal, it does fill the rifling grooves with jacket metal until all hope of accuracy is lost. So, the metal fouling has to be removed with a combination of chemical and mechanical action.
The modern .22 rimfire, in sharp contrast, uses clean-burning powder, clean priming and shoots clean lead bullets at low velocities. Nothing in its makeup or operation requires frequent cleaning. Those who shoot .22s can get away with not cleaning their guns for many hundreds and even thousands of rounds. Eventually, there will be a buildup of powder fouling even in these clean guns, but the contrast with centerfire guns is vivid.
Finally, there are the airguns. They neither burn powder nor use primers, so there’s no residue. They shoot at low velocities (compared to many firearms) and use clean lead pellets, so there’s little metal fouling. Only with some of the more powerful airguns do the velocities get fast enough to scrape off some lead from the pellets. And some barrels seem more prone to scrape off lead than others. That, alone, is the sole cause for buildup in an airgun.
In contrast to a firearm, an airgun can be fired tens of thousands of times between cleanings…and some lower-velocity airguns may never need cleaning at all. Those with brass or bronze barrels are entirely impervious to cleaning requirements.
The time to clean your airgun is when the accuracy falls off, not before. Do not clean an airgun barrel on a regular schedule — they simply don’t need it.
2. Disassembly without a plan
I’ve done this and so have many of you. The gun isn’t working right, so we take it apart to find out why. Then, we haven’t got a clue how to get it back together. That results in a basket case of parts that somebody else will be able to buy for a song. Don’t create bargains for others! Before you take an airgun apart, give some thought to what it takes to put it together again.
The way to do this is to first research the gun on the internet, to see if there are any disassembly or assembly problems. If there are known issues with a gun, there should be plenty of information on the internet.
Another thing to look for is if any special tools or equipment are needed. With spring guns, you usually need a mainspring compressor to safely disassemble and assemble the gun. And if you’re disassembling a BB gun like a Daisy Red Ryder, you need to make a special fixture to hold the gun while the mainspring is compressed and parts are removed. Unless you have three arms, this fixture is absolutely necessary.
Then, there are guns that are assembled during manufacture in ways that make them almost impossible to repair. One good example of this is the barrel of a Benjamin 392, which is soldered onto the pump tube at the factory. If the solder joint is ever broken, it’s next to impossible to repair. That’s because the joint is very long and is difficult to keep an even heat on the entire joint at the same time. The solder flows in some places, but clots in others. When you move the heat to the places where it’s clotted, you lose the solder that flowed before.
Don’t attempt repairs or modifications unless you know you can do the entire job. Better to spend some money to get the job done right by an airgunsmith than to charge in and break or lose some irreplaceable part.
3. Over-oiling
Some of the new owners’ manuals tell people to oil the compression chamber on a frequent schedule. While oiling was appropriate for guns with leather piston seals, the newer synthetic seals don’t need nearly as much. Over-oiling causes detonations that can damage the gun if they’re allowed to continue; and once they start, there’s almost no way to get them to stop. All spring guns diesel; but when they go off with a loud “bang,” that puts a strain on the mechanism.
I always like to err on the side of under-oiling because all that does is make noise during cocking. Over-oiling causes problems, though, and in extreme cases the airgun must be disassembled and dried out.
There are places to oil besides the compression chamber. Linkages need a drop every now and then, and the wood parts can always benefit from a Ballistol wipedown.
The other place oiling is necessary is on the tip of each fresh CO2 cartridge before it is pierced. The best oil for this job is Crosman Pellgunoil, and a CO2 shooter needs to always have some on hand. The oil is blown through the gun’s valve when the cartridge is pierced; and it gets on all the sealing surfaces, making a tight seal against gas loss. It’s the No. 1 maintenance action a CO2 gunner can take, and you absolutely cannot overdo it.
4. Under-oiling
So, what happens when an airgun is not oiled enough? It makes noises to tell you. Spring-piston guns will honk like a goose when they’re cocked if there isn’t enough oil on the piston seal. Mainsprings will crack and crinch when cocked as they slip their coils when they don’t have enough oil. And the fork that the breech sits in will become shiny if there isn’t enough grease between it and the breech. Also, the cocking effort will increase dramatically.
CO2 and pneumatic guns will develop slow leaks when they need oil. Their seals cannot do the job without a thin film of oil on all their surfaces. But if the gun is holding air, stop with the oil — except in the case of CO2 guns, as noted before.
5. Over-pressurization
This fault is as old as the hills and is a classic mistake a newcomer will make. If 10 pump strokes give X amount of power, shouldn’t 15 pump strokes give 1.5X? No! In fact, they do just the opposite. Over-pump a pneumatic or overfill it from a scuba tank, and the velocity takes a nosedive. It will drop all the way to zero, at which point the valve is locked shut by the excessive pressure in the gun. Imagine a door being held shut by several strong people. No amount of pushing will open it. You have to wait for some of the people to leave or, in the case of the gun, for some of the internal pressure to drop. That can take weeks and even months!
A pneumatic gun is designed to work within a certain pressure margin. Too little pressure and the power drops. Too much pressure and the power drops. Remember it this way — putting more gas into a car’s tank will not make it go any faster.
With CO2, you don’t have to add pressure; and in fact, there’s no straightforward way to do it. If you were to increase the gas pressure somehow, all that would happen is more gas would condense to liquid. The pressure would remain the same. But if the outside temperature should go up, the gas pressure will increase as well because the gas pressure is dependent on temperature. Operate your CO2 guns when the temperature is between about 60 degrees and 90 degrees F. And don’t leave a CO2 gun lying in the direct sun, even on a relatively cool day, because the gun will absorb the sun’s heat and will go into valve lock.
There you go — 5 simple things to remember about airguns and their operation. Perhaps our readers can suggest more?
Corn oil for lubricating spring-piston airguns
by B.B. Pelletier
Last week, our new reader, Cantec, mentioned that several gentlemen were advising the use of corn oil for lubricating the compression chambers of spring-piston airguns. I know exactly where this recommendation came from and how it should be viewed, and I wanted to share this with you today.
Corn oil?
Yes, I’m talking about common corn-based cooking oil. Wesson oil is the most popular brand here in the U.S. Why would anyone recommend using corn oil in a spring-piston airgun? I want you to know the entire truth so you don’t make any serious mistakes with your guns.
Good old corn oil that’s most often used for cooking has also been used to lubricate some spring-piston airguns.
WD-40
In my role as a firearms enthusiast, I used to put WD-40 on all my guns. It smells so good and guns always look so nice after they have been wiped down with it. So, when the Army sent me to Germany for four years, I sprayed WD-40 on all my guns before storing them in my mother’s attic, thinking I was protecting them against the ravages of time. What happened, instead, was that the WD-40 dried out and left every gun covered with a thick coating of yellowish residue that proved nearly impossible to remove. Only more WD-40 would dissolve it, and in one case the silver plating on my collectible second generation Colt 1851 Navy cap and ball revolver was destroyed! Each gun took weeks to clean, because the residue had gotten into all the cracks and tight places and had to be scraped out with tools.
Several years after that experience, I joined an horology club and attended their meetings for about a year. These are guys who fix watches and clocks, and they had one thing to say about WD-40. Don’t ever use it on a clock! They knew all about the yellow coating it leaves, and several members had horror stories about removing it from clock gears. Apparently, not even ultrasound tanks can remove all of it.
Before you rise up to defend WD-40, know that I use it, too. For certain jobs, it can’t be beat. But not for protecting the finish of a gun. Use Ballistol for that.
What does WD-40 have to do with corn oil? Everything. Like WD-40, corn oil dries and leaves a waxy film on anything it comes in contact with. And that’s why it was originally recommended for spring-piston airguns. Not all spring-piston guns, you understand. Just the ones from China.
Duane Sorenson, who used to work at Compasseco in the 1990s, recommended corn oil for all his Chinese guns because of the waxy buildup. He reasoned that the wax filled in the rough machining marks left inside the cheap Chinese compression chambers, eventually building up to the point that compression increased. He was an active proponent of corn oil in spring guns, and I think many thousands of shooters were told by him to use it.
Duane also said the flashpoint of corn oil was very high, so using it would stop dangerous detonations. As far as I was able to test for that, it did seem to work. But — and this is the point of today’s report — corn oil is not recommended for a sophisticated spring-piston airgun powerplant. The current crop of Tech Force guns do not have compression chambers rough enough to benefit from its use.
Time is the criterion
Duane was advising corn oil for airguns like the B3 underlever and the TS45 sidelever. Those guns really did have rough compression chambers that could benefit from a product that infilled their machining marks. But at the same time he was recommending corn oil, Sorenson was also pushing their Chinese manufacturing partner to better finish the insides of their compression chambers. The result was the Tech Force 36 underlever, which was very smooth inside, and later the Tech Force 99, which was even better.
But while this improvement was happening, Duane was still selling lots of the older and less expensive Chinese spring guns that were still very rough. So, he continued advocating corn oil, even as the many of the guns he sold were getting better and had less need for it.
I tested it
Duane was so insistent on corn oil being a miracle-product that I bought a quart of the stuff and began experimenting with it. That was how I learned that it doesn’t detonate. While I was testing it, I was unaware of why corn oil was being recommended and the fact that many of the more modern chinese airguns didn’t need it.
I conducted several tests using corn oil for The Airgun Letter, but frankly I never got the kind of results Duane told me to expect. Part of that was because I was probably testing it on the wrong guns and part was because I wasn’t using it as much as Duane did. I never saw the long-term effects he told me about.
I expected to see an increase in velocity and a decrease in the total velocity variance. The velocity never increased as much as I had thought, but the shot-to-shot variation did decrease somewhat.
What about corn oil today?
This is the reason I wrote today’s report. Do not use corn oil in any modern spring-piston airgun! Corn oil is meant to solve a level of manufacturing crudeness no longer seen in modern airguns. Like many other things, time has changed the game. We no longer put oatmeal in our car radiators to patch small leaks, and we certainly no longer lubricate spring-piston compression chamber with corn oil.
Just as you don’t want a buildup of hard yellow film on the outside of your airguns from dried WD-40, you also don’t want the waxy buildup from corn oil on the inside. Use the products that are recommended for the job, like a proper grade of silicone chamber oil for the compression chamber of your airguns.
Crosman’s 160: Part 2
by B.B. Pelletier
Fresh from the closet, another fine Crosman 160 emerges into daylight. We’ll watch this one blossom.
Today, I’ll report on the cleaning of Jose’s Crosman 160 and the adjustment of the trigger. This rifle was quite rusty when I got it, so today it came out of the stock for a thorough cleaning. The barreled action comes out of the stock by removing one nut on the bottom of the forearm and by removing the safety switch. To remove the switch, it must be turned toward SAFE while you push it out of the triggerguard. It will pop right out when you get it in the right position.
The broken safety has been pushed out, and the nut removed from the stock. That’s a new safety to the left of the broken one. The barreled action is now ready to come out of the stock.
Once the action was out of the stock, I could see that it was far rustier than I originally thought. The rust that could be seen when the rifle was intact was just surface rust, but the stock was hiding deep active rust that had to be removed.
This was under the stock — heavy, active rust that must be dealt with!
I used Ballistol and a special scrubbing pad I bought at a recent gun show. A friend of mine says this pad looks like a stainless steel pot scrubber. All I know is that it removes all the rust and doesn’t harm the blue.
I used Balistol in a spray bottle and a special metal scrubber to remove the rust.
I was surprised at how fast the rust was removed. In all, it probably took no longer than 15 minutes to completely clean all the metal parts.
The trigger
With the gun finally clean, it was time to address the trigger. I mentioned in Part 1 that this trigger is one of the finest ever put on an inexpensive air rifle, and it can be adjusted to a very light, crisp pull. When I got the gun, the single-stage trigger had lots of creep and was breaking at 5 lbs., even. Something had to be done about that.
The Crosman 160 trigger is an adaptation of a 15th century crossbow trigger, where a rotating piece called a nut forms the sear that releases the hammer — in the case of the pellet rifle. The nut is a lever that’s shaped like a circle. It allows a small force (the sear) to overcome a greater force (the hammer spring) through leverage. No filing or stoning of the trigger contact surfaces is necessary, because the trigger doesn’t work like a conventional one.
From Sir Ralph Payne-Gallwey’s book, “The Crossbow,” (published in 1903) this illustration of a 15th century crossbow nut shows how a great force can be overcome by a smaller one.
But the Crosman 160 trigger is more sophisticated than the crossbow trigger. It allows the adjustment of the sear contact area and also the point at which the trigger stops. This gives the shooter a safe trigger that breaks cleanly, yet feels like an expensive precision target trigger.
The trigger in the subject rifle was about as filthy as I’ve ever seen. This trigger has a sideplate that allows the user to watch the adjustments of the parts and even to cock and fire the trigger with the parts exposed. Normally, this sideplate keeps the parts inside pretty clean, but you can see from the photo what I saw inside this one.
I’ve removed the trigger unit from the action here. It isn’t necessary to do this, and in fact you must be able to cock the rifle when you adjust the trigger, so leave it connected. I did this for cleaning purposes.
Compare this photo to the previous graphic, and you’ll see all the important trigger parts. This is before cleaning. The rusty red part at the upper right is the nut that’s the sear.
I removed the trigger blade from the trigger assembly and cleaned it outside the trigger box, but all other parts were cleaned where they were situated. Ballistol on cotton swabs worked wonders at removing the rust, dust and dirt. And it left all the parts with a lubricated surface.
The two trigger adjustment screws were stuck in place by dried grease, so Ballistol had to dissolve that before I could clean the threads. The final touch was to apply moly grease to the mating surfaces of the trigger blade and the rotating nut that serves as the sear. Then it was time to adjust the trigger.
Trigger adjustment
The first step was to back off the trigger return spring, which is located at the bottom rear of the trigger box. With this spring relaxed, you can feel the engagement of the sear much better.
Next, I adjusted the top screw, which adjusts the trigger/sear contact area. I set it very quickly because I’ve adjusted dozens of these triggers over the years and I know what they need. You may have to adjust the screw then cock the rifle and fire it several times to get the engagement you want. The engagement needed is very narrow, and it looks like the trigger is about to slip off the sear; so I always give the cocked rifle a bump test after adjusting the trigger, just to be safe. If I can’t jar the trigger off the sear, it’s safe.
The final screw to adjust is the trigger stop or overtravel screw. It stops the trigger blade after the sear has released, and the closer this is to the release point without impeding the trigger-pull, the better the trigger feels. Once the engagement area is okay, it’s easy to set this screw to stop the trigger immediately following trigger release.
With that done, I put the cover plate back on the trigger and shifted my attention to the S331 sight. By the way, Robert of Arcade explained in a comment that the S331 sight was actually made by Mossberg and not by Williams, as I originally said in Part 1. I changed the maker to Mossberg in Part 1, and now I’m telling you.
The rear sight on this rifle was loose when I examined it, so I removed it from the rifle and disassembled it for cleaning. Most of the parts are aluminum, but a couple are blued steel and suffered from rust to the point that there were pits left on their surfaces after the rust was removed. The detents are very crisp and easy to feel as you make the adjustments. This is a simple peep sight assembly, but it works very well and adjusts precisely, which is all you can ask of a sight.
Once the sight was clean and back on the rifle, I put the barreled action back into the stock. I had to use the old broken safety switch because the replacement I have is slightly too large to fit the hole. I’ll trim it down in a separate session so the gun has a complete safety switch. For now, I’ll just keep the rifle off safe.
How does it look?
Because the bulk of the deep rust lies below the stock line, the deep pits that appeared from cleaning do not show. What was above the stock line was mostly just surface rust that’s now completely gone. The metal on this rifle now appears to be 80 percent or better. The stock finish is still flaky and needs to be taken down all the way with sandpaper and reapplied, but it doesn’t detract from the rifle’s appearance.
And the trigger?
The trigger now breaks at one pound, even. It’s glass-crisp, and you would swear that it releases at just a couple ounces if you didn’t see the trigger-pull gauge. I think the owner will be amazed at the transformation this rifle has undergone.
Yet to come
I won’t bore you with the other mundane jobs like the safety and the stock finish, but I’ll test this rifle for accuracy. So, there’s one more report yet to come. We already know the velocity is in the right ballpark — 656 f.p.s. for a 14.2-grain Daisy pellet on a 90-degree day. But I want to show you the accuracy these old rifles can give with modern pellets.
Air Venturi Bronco with optional target sights: Part 4
by B.B. Pelletier
You know how your wife buys a new trash can for the kitchen, and it doesn’t match the front of the old refrigerator that you’ve been talking about replacing for several years? So, you buy a new fridge, but you want this one to have an ice dispenser in the door; so, you hire a plumber to run the water lines; as long as he’s there, you decide it’s time to replace the chipped sink with a new stainless-steel double sink; but as long as he’s under there, you might as well have him replace the water supply lines and the waste pipes. Then, your wife doesn’t like how the new sink looks against the old green Formica counters, and she wants those granite countertops you’ve been promising her ever since you forgot your 17th anniversary; but the new countertops won’t look right on the old painted cabinets, so you decide on some Scandinavian teak cabinets with glass doors; and now the chipped dishes look out of place. [Note from Edith: This is hypothetical. It's not a true story about us!]
So, seven months later, the total bill for the new trash can comes to 70 thousand dollars? Well, that’s what I seem to have gotten into with the Air Venturi Bronco. I was just testing the new Bronco Target Sight kit on the rifle, and I raked back the compost pile a little too far. So, today, you’re going to benefit from my puttering gone amuck.
I took a lot of heat from you guys in my last report. You didn’t like how I did things, plus I introduced the new Air Venturi Pellet Pen and PellSet and called it maccaroni without any warning! Well, shame on me!
I began today’s test by mounting the Hawke 4.5-14×42AO Sidewinder Tactical scope on the rifle. The Bronco has a hole for a vertical scope stop pin, so I was able to anchor the two-piece mounts rock-solid.
I thought I would back up just a bit and see just what the best pellet is for this rifle, and then see if there’s a difference between seating that pellet flush and seating it deep. I started at 10 meters with five-shot groups, just to weed out the pellets that were not worth pursuing. They were all pretty good, but the lightweight Air Arms Falcon was just a bit better than the rest.
I realize that this is a test of a peep sight, but my last report raised some questions about the rifle’s accuracy that I felt needed to be laid to rest before the test was continued. I’m validating the rifle before I continue reporting on the new sight.
Then, I backed up to 25 yards and shot two 10-shot groups. One was with the pellets seated flush with the end of the breech, and the other was with the pellets seated deeper, using the PellSet. Let’s look at my results before I analyze them.
Ten Air Arms Falcon pellets seated flush with the end of the barrel went into this 25-yard group that measures 0.531 inches. The group is reasonably round.
Ten Air Arms Falcon pellets seated deep with a PellSet made this 0.821-inch group at 25 yards. Nine of the ten pellets went into a group measuring 0.564 inches.
Conclusions?
Looking at both the shape and size of these groups, I would be tempted to say the flush-seated pellets shot best. And there’s no doubt that this Bronco can shoot. But let’s not make up our minds just yet.
See that “flyer” in the deep-seated pellet group? It wasn’t a called flier. The hold and release were perfect. There is no reason that pellet should be that far away from the rest of the pellets at 25 yards.
What I’m not showing you are some other 10-meter groups with different pellets that also had strange fliers like this one. I had removed both the front and rear sights, so we can’t blame the front sight screws for being too long. But something is happening with this rifle that’s unusual.
Edith questioned me in the same way that I know the rest of you are going to question me. Didn’t I have good groups in the past? Why is this rifle suddenly shooting like this?
I went back and looked at the groups I shot in Part 3 of this report. If you do the same, you’ll see a couple “fliers” in those groups, as well. The difference is that those groups were shot at 10 meters instead of 25 yards.
So, then I went back to the 7-part report I did on the Bronco and examined those targets. In Part 5 of that report, I shot the rifle with a scope at 25 yards and guess what? There are “fliers” within some of the groups.
What’s happening?
I think the Bronco I’ve been testing is extremely accurate, but it has also been throwing fliers like this all along. I chalked them up to my poor shooting instead of something else. Now that I’ve examine the rifle under the microscope, I’m not so sure it was me. I think this rifle has been tipping pellets all along. It’s only when the gun is fired at 25 yards that this becomes evident.
I think this has gotten worse recently, but I cannot say with certainty what’s causing it. It’s clear from the two groups shown here that the rifle can really shoot, but I think it can do even better than it currently is.
I have a plan to try to remedy this situation; and, at the worst, it will not affect the accuracy of the rifle. But if I succeed, this rifle could shoot smaller groups than you see here.
I need to try my remedy before returning to finish the report on the peep sight kit, because I think it has been affecting the results. And there’s a second problem I’ve identified with the peep sights that has nothing to do with the sights, themselves, but with how I’ve been sighting the gun. I’ll describe that problem in detail for you and tell you how to easily avoid it.
Til then!
Air Venturi Bronco with optional target sights: Part 3
by B.B. Pelletier
Today is the day you find how I improved the accuracy of the Air Venturi Bronco rifle I’m testing with the Bronco Target Sight kit. I asked you to guess what I did to get better groups, but only Fred of PRoNJ got it right. I thought this would be a straightforward test and that one range session was all I needed for this rifle. After all, I already did a 7-part report on the gun, so there’s been plenty of time to get to know how it shoots. In fact, I even installed a Williams peep sight on the gun, so I even know how it shoots with that. This was just supposed to be a test of the Bronco Target Sight kit and nothing more. But man plans, and God laughs!
Yesterday, I told you about the front sight screws and the barrel that obviously needed cleaning. Afterwards, I was not rewarded with those perfect groups I’d anticipated. The groups I got were better than before the rifle was cleaned, but they were still bad for an accurate rifle at 10 meters off a rest. Something else was needed.
The artillery hold
How many of you guessed that the secret to good shooting was the artillery hold? Guess again, because I saw no difference between resting the rifle on the flat of my palm and on the backs of my fingers.
One thing I did rediscover was the need to hold the Bronco absolutely “dead” in my hands rather than with any tension built in. For its power level, the Bronco seems to be on the twitchy side as far as hold sensitivity goes. So, before you shoot, it’s imperative that you relax all the way and allow the rifle to settle in wherever it wants to. Then, you have to shift your hands and body until it settles in with the sights very close to on-target.
But that wasn’t the secret I was looking for because the groups were still on the large side. Then, something cool happened. As you know, my friend, Mac, has been visiting us; and while he was here, I got a couple spring-piston air rifles to test before they come to market. I’ll be starting some reports at the end of this month, so I asked Mac to test the rifle while I worked on other things. It’s never difficult to get him to test a brand-new airgun!
One of the pellets he selected to test the rifles with was the venerable RWS Hobby, which is the lightest all-lead pellet around. Hobbys are often among the most accurate pellets for spring-piston airguns, and they did really well in these new rifles, so his choice seemed obvious. Since the Bronco is also a spring-piston gun, I wondered if Hobbys might do well in it.
Did Hobbys shoot better?
Yes, they really did. They gave groups that were in the ballpark for the rifle as it was now performing with the clean barrel, but they weren’t the groups I’d hoped for. But something drove me to continue to shoot them. I guess I was thinking about the pellet seasoning effect we talk about. As I was shooting, another thought popped into my head.
Two years ago I was testing a Hy-Score 801 — a Belgian-made breakbarrel spring-piston air rifle that has a pellet seater built into the gun. It sits above the breech and swings down to push the pellet deep into the breech. When I tested it, the seated pellets increased in velocity by 100 f.p.s. and also grouped closer. Could that same thing be true for the Bronco, I wondered?
Well, it didn’t take much to test the pellet-seating theory, because I’ve been testing the Air Venturi Pellet Pen and PellSet for some time. But this was the first time I had occasion to use the adjustable PellSet tool to push a pellet into the breech of an air rifle! Until now, I’ve always used a Bic pen, but this new tool is adjustable so I can control the depth to which each pellet is seated. And once the tool’s adjusted, every pellet gets seated to exactly the same depth. Consistency is paramount to accuracy, so that’s very important.
Success!
The moment I began seating the pellets deeply with the PellSet tool, the groups shrank to an acceptable size. It looked like a television infomercial, because the difference before and after was night and day. I shot another group but didn’t seat the pellets. I held the rifle as carefully as I had when the pellets were seated deep, just to eliminate any bias. I’m not saying there still isn’t some bias in my testing, but the results of seating the pellets looks very promising!
This PellSet tool is an adjustable pellet seater that hangs around your neck and seals each pellet to the correct depth in the breech. Using it immediately tightened the Bronco’s groups!
When you load a pellet manually, you seat it flush with the breech like this.
The PellSet tool enables you to seat each pellet to the same depth in the bore. The tool is adjustable so you can fine-tune it.
Ten RWS Hobby pellets seated flush with the end of the barrel grouped in 0.916b inches at 10 meters. While not a great target, this demonstrates that the Bronco wants to shoot Hobbys well, because 8 of the 10 pellets made a group about half the size of the large one.
When the Hobbys were seated deep into the breech, they grouped into this 0.72 inch group. This is much better than the first group and clearly shows what deep-seating can do. But notice there’s still one flier in this group.
When I saw the difference between the deep-seated and flush-seated pellets, I believed I was on to something. But one result doesn’t make a conclusion, so I shot another two groups. This time, I was very careful with each shot to apply the artillery hold correctly.
The second group of flush-seated pellets was tighter than the first, though not as tight as the first group of deep-seated pellets. Only a single flier this time. Group measures 0.845 inches between centers.
The second group of deep-seated pellets gave this 0.516 inch group. No fliers at all. This is the accuracy potential of the Bronco!
Conclusions
There was a lot to cover in this test. First: I found that the longer front sight screws do not present any problems as far as accuracy is concerned. That was a needless concern.
Next, I discovered that the barrel wasn’t just dirty — the bore was actually constricted at the muzzle. Cleaning the bore (but not with J-B Non-Embedding Bore Cleaning Compound this time) did improve accuracy, but not as much as I’d hoped. Something else was needed.
I had shot decent groups with this rifle in the past, so it is accurate. After cleaning the barrel, I almost got groups as good as before, but not quite. However, I’d been shooting 10 shots at 25 yards before and only five shots at 10 meters. Any direct comparison between before and now was impossible.
Switching to RWS Hobby pellets was good, though Hobbys may not be the most accurate pellets for this rifle. But by staying with them, I eliminated any other comparisons that might lead me astray. I also seasoned the bore, so no one can say that accuracy suffered from switching pellets.
Finally, I used a pellet seater, and not just any seater, but one that’s adjustable so I can set how deep the pellet goes. This tool has a lot of potential for improved accuracy in lower-powered spring-piston airguns, and I plan on using it in a lot of future tests.
Bottom line
The Bronco Target Sights are a nice addition to the rifle and far less expensive than any alternatives. A scope would work well, too, but for those who like iron sights, this sight set might be the best way to go.
Air Venturi Bronco with optional target sights: Part 2
by B.B. Pelletier
We get requests all the time for basic maintenance articles and fundamental articles about how to diagnose an airgun and make it shoot better. Often, I refer readers to blog reports I’ve done in the past, but today (and tomorrow!) is a blog report with something for almost everyone. It started out as a simple test of my Air Venturi Bronco rifle with different sights, but it blossomed in several different directions — answering many questions and raising issues about which many readers have indicated an interest in the past.
I didn’t plan on this report turning out the way it did. This special two-part report (today and tomorrow) is a serendipitous journey of airgun discovery. It began when I mounted the optional Bronco Target Sight kit on my rifle and thought I would be demonstrating just how accurate a Bronco can be. (The Bronco is also sold with the target sight kit installed.)
Heck (I thought), there’s no risk here. I’ve shot this same Bronco before and I know how accurate it is. What could possibly go wrong?
What, indeed. If you click on the link to Part 1 of this report provided above, you’ll see that the first groups I shot with the Bronco and its new target sights were anything but encouraging. If this had been a different rifle I might have been tempted to write it off as inaccurate (I said tempted — not a sure thing), but because I’ve shot this exact same Bronco several times in the past with great results, I knew it was something other than the rifle’s inherent accuracy at fault.
Back-bored muzzle
You readers guessed what the problem could be, and Mac and I conversed at the same time. Mac owns a Bronco, too, and he knows how accurate it is.
One early theory was that the new longer front sight mounting screws might be protruding into the rifled barrel and clipping the pellet just before it leaves the muzzle. I had noticed when mounting the four front sight riser plates that the screw holes are drilled deep, so I checked them and discovered they are drilled all the way through the barrel. The kit has two longer screws that are needed because of the four riser plates, so was it possible that one of those screws was hitting the pellet as it passed through the bore?
The four front sight riser plates require longer mounting screws. Was one of them touching a pellet?
But Mac told me the barrel was back-bored. The muzzle is not where you think it is, but it’s about seven inches deep inside the barrel — behind the front sight. Back-bored means that instead of being crowned at the end of the barrel, the muzzle is sunk deep inside the barrel with a deep-hole drill. Doing this protects the muzzle from damage and preserves accuracy longer. It can also restore accuracy to rifles that have been cleaned from the front instead of the breech. When cleaning rods scrape against the sides of the muzzle they wear the metal and cause accuracy loss. Mosin Nagant rifles are often found with back-bored muzzles.
The true muzzle of the barrel is located at the tip of the cleaning rod. So, the front sight screws are not interfering with pellets before they leave the barrel.
Look inside the barrel
Once I confirmed where the true muzzle was, it was obvious the front sight screws could not be interfering with the pellets before they left the muzzle. But what about after they left? Could a pellet still be touching the edge of a screw after it exited the muzzle?
This time, the answer was less exact. From what I could see with an endoscopic light down the bore, the screws were probably not protruding deeply enough to touch the pellets in flight unless the pellets were yawing wildly. And if they were yawing wildly, they were never going to be accurate anyway. So I stopped looking at that and checked the cleanliness of the barrel next.
Surprise!
The barrel had a constriction right at the muzzle! A brass bore brush passed from breech to muzzle (the true muzzle — not the end of the barrel) stopped abruptly at the muzzle. Something was constricting the barrel right at the point the pellet exited. The barrel needed to be cleaned, but this constriction was so abrupt that it felt like a large burr had been raised right at the muzzle. But the muzzle is seven inches deep inside the barrel, so that’s next to impossible!
The only solution was to clean the barrel, and I started with a clean brass bore brush. Don’t waste your time with a nylon brush. It isn’t stiff enough to remove the metal if there’s any. As long as the barrel is made of steel, like the Bronco’s barrel is, you cannot damage it with a brass brush.
After 20-30 passes the brush was meeting no resistance, so I then cleaned the barrel with Otis bore solvent until the patches came out clean. Now, the barrel was ready to perform at its best!
On to shooting
After all of this, I felt ready to shoot the rifle and expected it to do well. A quick read of Part 1 showed me that I tested it with H&N Finale Match Rifle pellets and JSB Exact RS pellets. Those were the first two pellets I shot. The range was 10 meters, and each group got 10 shots.
I would have loved to have shot two beautiful targets and ended this test right there, but that didn’t happen. Yes, the groups were somewhat smaller than those shot in part 1, but they were not good groups — not for a Bronco, anyway. The H&N Finale Match Rifle pellets grouped 10 in 1.059 inches — compared to the group in Part 1 of 1.668 inches. And the JSB Exact RS pellets grouped 10 into 0.82 inches this time –compared to 1.169 inches in Part 1. Yes, these are smaller groups, but they aren’t small enough for the Bronco at 10 meters. Something else had to happen.
I found the secret
This is where I’m going to end the report today. Tomorrow, I’m going to tell you what happened to change the outcome of the test. Yes, a different pellet was used, but that wasn’t the big news. In fact I’m convinced that I’ve found the secret to increasing accuracy with any Air Venturi Bronco — shooting any pellet!
You have a day to wonder, ponder, guess and discuss. Let’s see how smart you guys are.
What did I do that was different? A hint — I’ve done it before with similar results.
