Posts Tagged ‘mainspring compressor’
El Gamo 68/68-XP — A futuristic airgun from the past: Part 6
by Tom Gaylord, a.k.a. B.B. Pelletier
Part 1
Part 2
Part 3
Part 4
Part 5
El Gamo 68 is a futuristic breakbarrel from the past.
I last reported on this rifle on August 8 of last year. And that was Part 5! I had just tuned the rifle with a new mainspring and proper lubricants and was wondering what the changes would be. I was ready to report on it several months ago when I discovered that it wouldn’t cock. After fiddling with the trigger adjustments awhile with no success, I set it aside and moved on — thinking that the gun would need to be disassembled.
I disassembled it last week and discovered there was nothing wrong! The sear was working properly, or at least it seemed to be when I played with it as the gun was disassembled. I relubricated everything and put it all back together and was going to write Monday’s report on it. But the trigger still didn’t work! ARRGH!
This time, I remembered that when I got the gun the trigger was also a bit iffy, so I fiddled with the adjustments WAY outside the normal realm and, presto! I got it working again. Oh, it took a couple hours and there were some accidental discharges when the barrel was closed (direct sear!), but I solved all that by giving the sear way more contact than it needs.
Now the trigger releases at about 12 lbs., but at least it’s safe. Today, I’ll share with you how the tuned gun does at 25 yards — heavy trigger and all.
One other thing I did to the rifle was lubricate the leather piston seal with 10 drops of 3-in-One oil, leaving the rifle standing on its butt for two days afterward. The oil was allowed to slowly soak into the leather, which it did, but to protect the carpet and walls (Edith–Are you listening?) I put a long drop cloth in front of the rifle when I shot it.
Today’s test is a deviation from my normal pattern. I’ve tuned this gun and not yet reported the new velocities, and yet here I am shooting for accuracy. I decided to do it that way; and if I got good results, I would test the velocity next. I’m not changing the usual way of doing things — this is just an exception.
RWS Hobby
The first pellet I tested was the RWS Hobby. I chose it for its light weight and because it’s often accurate in lower-powered spring rifles and pistols. Sitting 25 yards from the target, I have to admit that I was wondering if the rifle had enough power to hit that target — let alone shoot a decent group.
Five of the first 10 pellets were detonations from the oiled piston seal. And the smell of burning oil was in the air. The Hobbys landed in a vertical group that was pleasingly tight from side to side. I was prepared to blame the verticality on the dieseling, but the truth is, that wasn’t the problem. The gun just doesn’t want to shoot Hobbys at 25 yards. That’s not too surprising since 25 yards is about the maximum distance for any wadcutter pellets, in my experience.
Ten Hobbys made this 2.151-inch group at 25 yards.
Air Arms Falcon
The second pellet I tested was the Air Arms Falcon, a 7.3-grain dome that’s often accurate in spring rifles. I used the spotting scope only on the first shot, which was a detonation, to make sure it was on the paper. There were 4 detonations in the 10 shots. I didn’t look at the target again until I walked down to change it. Boy, was I surprised by what I saw! To paraphrase Crocodile Dundee, “Now, THAT’S a group!” For open sights at 25 yards and 65-year-old-eyes, it ain’t too bad!
Ten Air Arms Falcons went into 0.898 inches between their two widest centers. This is an acceptable group for this rifle at 25 yards.
Remember, I’m shooting 10 shots — not 5. So this kind of group really proves the rifle can shoot. It also proves this old man can still hit things when the rifle does its part! So much for the problems of the droopers and gas springs! I needed this validation after some of the disappointing tests I’ve done recently.
The heavy trigger apparently is not causing much of a problem for me. I think that’s because the rifle is rested. If I were shooting offhand, I’d want a lighter trigger-pull.
JSB Exact RS
Next, I tried JSB Exact RS pellets. This is another 7.3-grain dome from JSB (JSB also makes Air Arms Pellets) and is very often accurate in many different airguns. And this is one of them. The group is slightly larger than the Falcon group, but the two are so similar that I would call it a tie.
Ten JSB Exact RS domes went into 1.028 inches. Though not quite as small as the Falcon group, I would rate both pellets about equal in this rifle.
RWS Superdome
The last pellet I tried was the RWS Superdome, which often does well in lower-powered spring rifles. This time, however, it didn’t. Ten pellets produced a 1.765-inch group. It didn’t disappoint me, though, because the Falcon and JSB RS groups looked that much better. It showed that the earlier Hobby group wasn’t just a fluke of bad luck — the gun simply likes what it likes.
Ten RWS Superdomes made this 1.765-inch group.
Evaluation
This test was calming for me. It was slower than many of the tests I’ve run in the past month, and the results were more based on me as a shooter rather than on the equipment. I find that I like that a lot!
The El Gamo 68 XP is operating well right now, except for the heavy trigger that I’ll probably keep just as it is for a while. The tuned powerplant is now smoother with less of a jolt. I noticed in this test that each pellet has a firing characteristic of its own. The two JSB pellets were definitely the smoothest of the four tested, and the Hobbys were the roughest.
This is such an odd airgun, with the fat heavy butt and no forearm to hold. Yet, it shoots like a thoroughbred. With the new tune, it cocks smoothly and just feels good to shoot — I don’t have any better way of describing it. I wish you could all try one, but since you can’t, I will, again, recommend the Air Venturi Bronco, which is the closest thing still being made today.
El Gamo 68/68-XP – A futuristic airgun from the past: Part 5
by B.B. Pelletier
El Gamo 68 is a futuristic breakbarrel from the past.
I’m sure many of you imagine that I’m immersed in airguns all the time, which is true. That my office is filled with all sorts of models (it is) and that my workshop bench is strewn with parts of projects in process. There’s just one problem with that view. I don’t have a workshop. When I really need a lot of room, such as for today’s report, I usually move to the kitchen, where I do my work on that time-honored bench — the kitchen table!
The other thing most readers don’t appreciate is how whipsawed I am with time. I can’t afford to spend a week or even two days on a project anymore. Back in the days of The Airgun Letter, I had one month to crank out the stories that are now written in about four days! If I spend more than three hours on a project before starting to write about it, I’m working on a 12-hour day because the writing and photography take so much more time than the actual testing. And so it was with some trepidation that I approached today’s report, which is a disassembly, evaluation, cleaning and lubrication of my Gamo 68 breakbarrel air rifle.
I wanted to do this because the 68 shoots very suddenly. It doesn’t vibrate like many spring guns, but the thump when it fires is very heavy — way out of proportion with the power of the gun. The trigger is very heavy, and I wanted to see what might be involved in bringing it down. It’s crisp enough, just too heavy for the release.
Because of the potential time element and the fact that I have no room for another disassembled airgun, I studied the rifle carefully for two months — the way a diamond cutter examines an important stone. And with all that study, I still did not recognize the way the gun is assembled. But one look at a schematic sent by David Enoch showed me what to do.
Only three screws have to be removed to take the action out of the stock. That’s no different than any other breakbarrel, but the location of the third screw is certainly different! It’s at the back of the spring tube.
This photo shows the action out of the stock. One extra screw was removed. The one below the triggerguard does not hold the action in the stock. It’s one of two screws that hold the trigger unit to the stock, and it doesn’t have to be removed to get the action out of the stock.
With the action out of the stock, you have access to disassemble the mechanism and do what I ended up doing to the rifle. The trigger is really a complex bullpup unit that’s entirely separate from the barreled action. By “bullpup,” I mean that the trigger blade does not directly contact the sear. It’s located many inches forward of the true sear and is connected by a long lever inside the trigger unit. If I want to improve the trigger-pull beyond what simple adjustment can do, I need to remove this unit from the stock to get access to the pins and levers.
I decided to leave that task for another day, as working on the powerplant was all I had time to do in this session.
You’re looking down into the aluminum stock that holds the spring tube. The trigger unit runs from almost all the way on top, where the trigger blade is located, to all the way on the bottom, where the true sear releases the piston. It’s a complex bullpup unit that must be removed as a unit for work. You can see the steel channel that holds all the trigger parts.
Because of the way the Gamo action is designed, I could set the trigger aside and go to work on the powerplant. The end cap is held in the spring tube by a single large pin that must be drifted out. The action was installed in a mainspring compressor for this next step.
Here you see the barreled action in the mainspring compressor with the large pin drifted out. The pin is on the table, next to the hammer handle. The spring tube is ready to come apart.
Moment of truth
Taking a spring-piston powerplant apart for the first time is always a surprise. You never know how much compression the mainspring is under, even when relaxed, and how far it will come out of the gun before it’s fully relaxed and the gun can be removed from the mainspring compressor. It was a real surprise this time, for the spring came out several inches before fully relaxing. If I had just drifted the pin and tried to hope I could hold the end cap with my body, I could have broken bones!
Like a python that swallowed a telephone pole, the mainspring just kept coming out of the spring tube until it was this far! As you can see, I didn’t have much more room on my adjustment screw.
Once tension is off the mainspring, the rifle can be removed from the compressor. The end cap, spring guide and mainspring can now be removed. The piston, though, is still held in the rifle by the cocking link. You must disconnect the link from the piston before it will slide out of the gun.
The 68 has an articulated cocking link, and I noticed a spot at the front of the cocking slot that was enlarged for the removal of the cocking link. That told me that I did not need to remove the barrel from the action to disconnect the link from the piston. Just line up the link end with the enlarged hole, and the end pops right out.
The cocking link is two pieces.
The end of the link can be removed from the spring tube through the enlarged hole at the end of the cocking slot. The two-piece cocking linkage helps you do this.
The mainspring and piston both told me this gun had probably never been apart before. The grease looked like factory grease, and there were many years of accumulated dirt and grime on all the parts.
The piston has a leather seal that looks brand new. It was a bit on the dry side. After I assembled the rifle, I lubricated it heavily. I’ll continue to do that many times over the next few months, until I’m satisfied that the leather is oily and supple once more.
Leather piston seal looks good.
The piston itself is a very strange duck. It has to be, because the trigger is autonomous from the powerplant. There’s a window on the side of the piston at the rear where the sear catches it when the gun is cocked.
Here you see the entire piston, which is a machined steel part. The rectangular window at the end of the piston skirt is where the sear catches and holds it when the gun is cocked. Only the piston seal and the machined section at the rear touch the inside of the spring tube, so that’s where the moly lubrication goes.
The inside of the spring tube was as dirty as the piston and mainspring. I put paper towels over the end of a long-bladed screwdriver, dipped the paper in alcohol, and cleaned the inside of the spring tube and compression chamber. This would also be the time to remove any burrs from the cocking slot, but there weren’t any on this one.
After the entire powerplant was cleaned, I examined that long mainspring. After all those years, I thought it had to be canted — and it was, though not as much as I’d imagined. Rolling it on a flat surface revealed a wobble at one end, which translated to a jolt during firing. Hopefully, I had a suitable replacement.
I found several possibilities, but the best one proved to be a replacement spring for a TX200, of all things. It’s a special spring Jim Maccari made some years ago and it has collapsed coils in the center and at one end. As you can see in the picture, it’s a lot shorter than the spring that was in the 68. The wire is thicker, but there are so many fewer coils that I knew it would fit. The fit inside the piston was about the same as the factory spring, and the fit on the spring guide was tighter. So, this is a good replacement.
Factory spring above, replacement below. The new spring will certainly be under less compression when the gun is not cocked!
I coated the new spring with a thin layer of black tar and inserted it back into the piston. The front and rear of the piston were then coated with a heavy layer of moly grease and installed back into the spring tube. The cocking link was inserted back into the enlarged hole, where it contacted the piston for cocking.
The spring guide was coated with moly and slid inside the mainspring as far as it would go. The end cap was placed over the end of the spring guide, and the barreled action was installed in the mainspring compressor, once again. This time, the amount the spring stuck out was drastically reduced.
The spring guide is steel. It was coated with moly and slid back inside the mainspring.
The new mainspring has just begun to compress. It’s a lot shorter than the old one!
The gun went together without a hitch! And that was when I noticed for the first time that the entire job from start to finish had taken me only one hour — including photos! That’s as fast as I could tune a TX200 (assuming I would, which would never happen), and it doesn’t require a mainspring compressor. This wasn’t the time-killer I thought it was going to be.
How does it shoot?
The rifle cocked with 22 lbs. of force before this tune. Now it takes 28 lbs. to cock it, and the final sear lockup takes a final crunch that wasn’t there before.
The gun fires with 70 percent less jolting than before, but its just as quick as it was before the tune. The feel of firing is atypical of a lower-powered breakbarrel, just as it used to be. I can now feel a little vibration in the powerplant that I think was previously masked by the heavy firing jolt.
I still don’t know the gun. It will take a session of velocity testing and shooting for accuracy before I can finish this report. Since I’ve already tested the gun extensively before, I’ll combine both of those things in the next report.
A shrine built for a Feinwerkbau 124 – Part 6
by B.B. Pelletier
Tuning by Earl “Mac” McDonald
Part 1
Part 2
Part 3
Part 4
Part 5
The saga of tuning the FWB 124 continues. While he was here, Mac replaced the Mongoose tune in my 124 with a fresh Maccari Old School kit, which consists of a Blizzard piston seal, a short mainspring and a spacer that slides inside the piston ahead of the mainspring. This he cheerfully did.
You may recall that my 124 was giving an average of 800 f.p.s. with the Mongoose kit. I felt that was too slow and wanted just a little more — perhaps 840 with Crosman Premier lites. The words on Maccari’s website seemed to indicate that the Old School tune was the ultimate way to go, so I ordered one.
The kit arrived, and I was going to install it when the hospital adventure began. So, when Mac arrived, he had the time and I asked him to do it for me. He certainly knows how.
He had to use my mainspring compressor to get the rifle apart but was able to put it together with the Old School kit without using the compressor. No Black Tar dampening compound was used with this tune because the Old School kit is supposed to fit so well it doesn’t need it. Mac put some moly grease on the outside of the mainspring and buttoned up the rifle.
In the hospital, I waited with great anticipation for the results, which came the next day. According to Mac, the new tune averaged around 740 f.p.s. with Premier lites. Seven forty! I was devastated! Well, maybe Mac was reading the chronograph wrong. I vowed when I got home that I would check it.
I asked Mac to remove the hump on the piston seal, thinking it might be the cause of the lower compression. He used a Dremel tool rasp to cut the crown smooth, as I requested, but no change in velocity. So much for my theory of the wasted compression space caused by the high crown.
My check
I shot Premier lites and got the following velocities:
770
763
762
764
764
The shots were accompanied by a burning oil smell, so the powerplant may be over-lubricated at some point. I will disassemble it to determine what to do next. On some guns, I might suspect the compression chamber.
I’ve examined the 124’s compression chamber and know that it is in good condition, but allow me to show you one that is not. Remember the Slavia 622 rifles I tested for you a while back? If not, read this.
What to do?
My next step will be a teardown to check what’s going on inside this gun. I may be able to refresh the tune and get it up to snuff from there. If not, I may install another type of piston seal left over from 124 testing years ago. The journey continues….
A shrine built for a Feinwerkbau 124 – Part 5
by B.B Pelletier
Before I start, a couple of reminders. First is the Facebook event on Tuesday, April 8, at 8 p.m. Eastern. I’ll be on the Pyramyd Air Facebook page for an hour to answer questions you send in. To ask questions, you need a Facebook account and you must be a Friend of Pyramyd Air. Register early and don’t miss out.
Next, don’t forget the Arkansas Airgun Extravaganza, April 30 & May 1. This airgun show is open to the public on Friday, 10 a.m. to 6 p.m., and Saturday, 9 a.m. to 4 p.m. Six-foot tables are $50 each. Admission is $5. Kids 12 and under get in free with an adult. Dealer setup is on Friday, 8 a.m. to 10 a.m. Visit the show website here.
The show is filling fast, and it looks like it’ll be larger than last year’s Little Rock show, which it replaces. I hope you consider attending. I’d sure like to meet as many of you as possible, and I’ll be bringing several of my airguns to show and possibly to shoot, including today’s rifle.
Also, a word to show-goers. If you’re going to attend the show only on Saturday, come before noon. Airgun dealers get antsy toward the end of every show and start packing up early. Unlike gun shows, they’re not penalized for this. Get there while the show is still running strong.
Today, I’ll tell you what I did to the 124 after discovering that the Mongoose kit wasn’t performing up to my expectations. You may recall that it was shooting Crosman 7.9-grain Premiers at an average of 670 f.p.s. I had expected at least 840 f.p.s. Although the firing behavior was very smooth and delightful, I had hoped to break at least 800 f.p.s., so I continued to work on the rifle.
First, I removed the mainspring only and wiped off about 3/4 of the black tar grease. That still left enough to kill all vibration, and the velocity rose to about 700 f.p.s. That’s a gain of about 40 f.p.s. It’s possible to remove the mainspring without a total disassembly, so it was quick and I did it first to see what gains there would be.
Next, I completely disassembled the rifle and removed all the lubrication from the powerplant. I carefully relubricated it very sparingly, keeping the use of tar confined to the outer coils of the mainspring. That got me to 710-720 f.p.s., which was about as far as the Mongoose kit is going to take me.
I’d treated the Mongoose kit as a drop-in instant power booster, and apparently it’s not. It’s more of a 1970s-era 124 kit that needs to be coaxed to shoot as fast as possible–just like the factory 124. I discovered something very important about the piston seal. It’s domed. With that shape, it’ll never produce the absolute fastest velocity since the top of the dome stops it from compressing all the air in the chamber. It may seem like a small thing when you look at it, but this last bit of compressed air is where the big things happen. Maccari has made this seal to cushion the piston blow rather than develop maximum power, so consider that when you order your tuneup kit.
The Mongoose piston seal has a raised, dome-shaped crown. It cannot compress all the air in front of it.
Compare this Surrey 124 seal to the Mongoose seal. See how flat it is on top?
At this point, there were several different directions open to me. One was to start shimming the Mongoose mainspring for extra compression. That would boost power. Another was to abandon the Mongoose seal in favor of a flat one. That would compress the air more thoroughly and give more power.
I took a third step that’s not available to any of you. From my years of working on argues, I had other mainsprings available. I selected a stouter one that was shorter but had a spacer top hat on one end. The other end fit the spring guide very tightly because this was an experimental Maccari 124 mainspring. I retained the Mongoose seal for smoothness and assembled the rifle with minimal lubrication. No black tar because the new spring fit much tighter than the Mongoose spring. I used moly grease on everything. I knew I would lose some power with the Mongoose seal, but that was okay for now. All I wanted was a working 124 with decent power.
As I assembled the rifle, I also answered someone’s concern about the safety spring. They had heard it is a concern when assembling a 124, but I say as long as your spring compressor is a good one the safety spring is easy to install. Hopefully, the pictures will show you how it’s done.
This is the 124 trigger unit with the safety slide and spring removed.
Here’s the spring I’ve been calling the safety spring. It’s actually a trigger-return spring, but it presses against the safety slide.
And here’s the safety slide on top of the trigger unit. You can see the spring between the trigger unit and this slide. As the trigger unit enters the spring tube, the safety slide is pressed flat and retained. There’s really no difficulty installing these parts as long as you use a mainspring compressor.
Following this tune, the rifle is averaging 800 f.p.s. with 7.9-grain Crosman Premiers. While that’s not as much as I want, I’m fine with it for the moment. The gun fires quick and doesn’t vibrate when it shoots, so the tighter parts are as trouble-free as can be. The velocity varies between 783 f.p.s. and 802 f.p.s. Experience tells me this will tighten, and the average velocity will increase by 10-15 f.p.s. as this tune wears in.
I’d planned to test the rifle for accuracy at this point, but I’m not yet finished with the project. The barrel’s gunked up with oil and grease that I don’t want to clean out until I’m done tuning.
My plan is to now install a Maccari Old School kit and be done with it. This is the kit I used to install in 124 rifles 15 years ago, and I know I can expect a velocity over 840 f.p.s. with 7.9 Premiers. The best result I ever got is still averaging 880 f.p.s.
Well, this little adventure has turned into quite the saga, hasn’t it? I never envisioned spending this much time with this rifle. Now that I have, I’ve decided what to do with the gun in the future. I’ll keep the rifle outside the case and shoot it from time to time. It was silly keeping it tucked away where I got to see it only every couple years. That isn’t what this rifle was made for, and I intend getting the full value out of it.
Someone asked me what all this tuning does to the value of the gun. Well, the box only adds value in a non-monetary way. Yes, it’s worth more than a rifle by itself, but this is no collectible. It’s more of a curiosity. So, I feel the tuning does nothing but enhance the value of the gun. I won’t scope this rifle because of the pristine condition, but I will leave it out of the case as a shooter.
In the future, I will chronograph and also shoot for accuracy the vintage Beeman Silver Jet pellets, which–believe it or not, started this whole report in the first place.
On Monday, I’ll show you a 124 clone Vince sent to me.
A shrine built for a Feinwerkbau 124 – Part 4
by B.B. Pelletier
My enshrined 124.
Today, I’ll complete the tune on the FWB 124. A couple people have asked about this gun. What makes it so special? Well, it’s lightweight, accurate, easy to cock and shoots like a dream. It’s the very rifle AlanL has been searching for but doesn’t realize it.
Back in the 1970s, when the FWB first came to the attention of airunners, it was considered one of the most powerful springers available. Together with the BSF S55/60/70 and the Diana 45, it was one of those rare air rifles that would sometimes shoot faster than 800 f.p.s. Today, we wouldn’t give it a second look with numbers like that and here is what we would miss. We would miss owning a Mercedes SSK convertible, just because it doesn’t go as fast as a Mustang SVO. Nobody would give any thought to the fine coachwork, the burled wood dash or the exotic leather seats. No, they would all be focused on the speedometer and miss one of the finest examples of its kind ever to have been built.
What to expect
With a modern tuneup, like the one I’ve done here, the 124 should top 840 f.p.s. with Crosman 7.9-grain Premiers. I showed you the tuneup kit yesterday. Today I’ll install it along with some lubrication that I always do on a 124. Of course, this is one more reason for owning a chronograph.
Cutting up the old seal
Before I begin, I had some comments that I will now address. First, someone asked me how I cut the thick piston seal to remove it. I mentioned a special knife that I’d like to show you. This tanto-shaped blade comes on a Gerber Crucial multitool that Edith gave me for Christmas. I keep it in my desk drawer and it is one of the handiest multitools I’ve ever seen. The knife blade is very stout, so it handled this job like a breeze and a few passes over the Warthog got the blade sharp in moments.
A Gerber Crucial multitool has a tanto-shaped blade that was ideal for cutting the old seal into pieces, as shown previously.
Removal of old seal material
The second tip is for Derrick38, who says it can be tough to remove old seal material from a compression chamber. Yes, it can! But I found that the patch removal tool that goes on my Thompson/Center Hawken ramrod is very good at scraping in those tight corners.
The patch removal tool on a Thompson/Center Hawken ramrod is great for picking old seal material out of the crevices of the compression chamber.
Sizing the new seal
The first thing to address is the piston seal. This one fit pretty tight in the spring tube of the rifle, so I decided to remove some material from the edges. There are a lot of ways to do this, and I chose the easiest one because I’m a guy who likes simple. I held the piston with seal in my right hand and a piece of 220-grain sandpaper in my left hand and proceeded to scrub off a tiny bit of the edge of the seal.
This is the way to make the new piston seal a trifle smaller.
You have to know when to stop. I just wanted the new seal to fit in the spring tube with slightly less resistance, which it did after a few minutes of work. Next, I cleaned the inside of the piston with denatured alcohol and Q-tips. It was caked with dried moly or tar that had to be removed. The 124 piston is very heavy for the power the gun develops, so heavy pellets should work pretty well.
Lube the compression chamber walls
I had cleaned out the compression chamber earlier, so now it was time to smear moly grease on the inside walls of the chamber. For that, I use a dowel with a paper towel folded over the end and held on with a rubber band. It allows me to accurately coat the inside of the cylinder.
Moly grease on a paper towel on the end of a dowel is the way to lube the inside of the compression chamber.
Lube the piston
Next, I lubricated the piston before putting it back in the gun. I put a stripe of moly grease around the front with the seal and another around the rear where the piston flares out.
A stripe of moly grease around the piston seal and another one at the rear of the steel piston will keep things slipping along.
The piston can now be inserted back into the spring tube, keeping the cocking slot aligned with the slot in the spring tube. When the front of the piston is in the tube, that’s the best time to lubricate the rear of the piston and the piston rod. Shove the piston into the tube with the new mainspring.
A stripe of moly grease around the rear of the steel piston keeps the metal-to-metal contact lubricated.
Install the sliding shoe/cocking link
Once the piston is inside the spring tube, the sliding “shoe” that connects the cocking link to the piston can be lubricated and installed. A wide spot in the spring tube slot accepts this shoe.
The shoe is lubricated with moly grease on both sides and dropped through the wide spot in the spring tube. It rides on a special bearing surface on the piston, so that was also moly-ed before installation.
Lube and install the mainspring
Next it was time to install the new mainspring. Before I did that, the spring got a liberal coating of black tar, the open gear lubricant that deadens vibration. I smear the front half of the spring first, then insert it into the piston and use it to hold the spring so I can lube the rear half.
Caution–here is where I screwed up!
What the picture shows is too much black tar being put on the mainspring. I didn’t know that until the job was finished and the gun back together, of course, but I now have a rifle shooting 7.9-grain Premiers at 670 f.p.s. instead of the approximately 840 f.p.s. I expected. I used too much because Jim Maccari said the Mongoose kit I selected was a loose fit and needed tar to calm the vibrations. I hate vibrations, so I went overboard. The fix will be to take the gun apart and remove a lot of the tar I applied.
This is too much black tar. I will have to remove a lot of it.
One thing about fitting a mainspring to a rifle. The tightest end of the spring always goes over the spring guide in the rear.
Lube the baseblock and pivot bolt
The FWB 124 has a baseblock bearing on just the right side. The left side is plain. I smeared moly grease on both sides and also on the pivot bolt before it was inserted.
Moly on both sides of the baseblock and on the pivot bolt will reduce the cocking effort to the minimum.
The trigger unit is now pushed back into the spring tube, keeping tension on the safety spring as you go. When the bolt hole lines up, the bolt is screwed in and the job is just about finished. Just put the action back in the stock and you’re done.
Mainspring compressor make this an easy job.
The tuned rifle cocks easily at just 23 lbs. Beeman used to advertise the cocking effort at 18 lbs., but all the 124s (about a dozen) I have tested were around 21-23 lbs. So, we’re in the ballpark. Of course, the velocity is low, but I’ll take care of that in the next report. I’ll also shoot the rifle for accuracy with open sights.
The trigger
The trigger is one thing I never learned to adjust on a 124 and I used to think it was impossible, but I once owned Mrs. Beeman’s 124, which I named the Queen B. That trigger broke at less than a pound, so someone knows how to do the job. Just not me.
Irony at work
Of course, the new pliable breech seal was installed and the petrified “new” breech seal I had tried went back into the box with all the other ruined new parts. I find it incredibly ironic that the owner of this fine rifle had wanted to preserve it for all time and it didn’t last as well as a similar rifle used every day. I guess man plans and God laughs.
A shrine built for a Feinwerkbau 124 – Part 3
by B.B. Pelletier
My enshrined 124.
Before we start, I have an announcement. I’ll be on Facebook answering questions again on April 8th at 8 p.m., Eastern. The last time was during the work day, which may have been inconvenient for many people, so we’re giving this time slot a try. Please join me if you’re able. I’ll be answering airgun questions on Facebook on this Pyramyd Air Facebook page. To see the discussion and ask questions, you must have a free Facebook account.
Today, I’ll start the tuneup on this rifle, and I have some very interesting things to show you. I’ll get through the disassembly in this installment, and in the next part I’ll tune the rifle.
I purchased a Maccari Mongoose tune kit that includes the mainspring and seal. I also bought a new breech seal to replace the new one in the box that had hardened over the years. Finally, I bought some of Jim’s Heavy Tar and his moly grease, because I’m getting low on those supplies.
This is the kit and lubes.
Step one in disassembly is to remove the action from the stock. That’s two forearm screws and the front triggerguard screw. The moment the action was out, I saw clear evidence that this rifle had received some kind of tuneup in the past. I could see that the mainspring was coated with black tar, a product they didn’t even know about in the 1970s when this rifle was new. For a few minutes, I thought maybe I had done it and had forgotten I did, but as the gun came apart I saw proof that I had never been inside.
Once the action is out of the stock, it goes into the mainspring compressor. Blog reader Vince said that he doesn’t use a compressor, but the 124 is one of those rifles that really needs it. And here’s a big tip. When you adjust the compressor to receive the rifle, leave a lot of adjustment room on the screw that backs off the spring tension. You really need the room there.
The single bolt in front of the trigger blade holds the 124 action together.
Leave lots of room for the mainspring to back up.
I use a heavy cardboard pusher to avoid damaging the rifle’s finish.
The trigger assembly and safety slide came out without a problem, as did the mainspring. It was in very good condition; but I’ve purchased a replacement whose pedigree I know for certain, so I’ll replace it anyway.
With the tension off the mainspring, the trigger unit moved almost two inches back. It will need an extra inche to install the new spring.
The trigger unit contains the mainspring guide. The old spring is in pretty good shape. That’s the assembly bolt that held the rifle together.
Before the piston will come out, it must be disconnected from the cocking link. For that to happen, the barrel has to come off the action fork. When I pulled off the barrel, I saw no evidence of moly grease on the sides of the baseblock or on the pivot bolt. They were lubricated with a light machine oil. That’s a clear indication that I’ve never been inside this airgun.
The cocking link fits into the cocking shoe that is held captive inside the piston until the barrel is disconnected from the spring tube.
The pivot bolt is the large screw on the right. Take it out and the baseblock separates from the action fork.
With the barrel off, it’s possible to slide the cocking link far enough to the rear of the cocking slot that the FWB cocking shoe can be removed. There’s a widened spot in the cocking slot just for this.
Now the spring tube is disconnected from the barrel and the piston slides out easily. When I saw this one, I knew the seal was gone. Just look at the picture!
A classic case of a disintegrated piston seal, with the new one for comparison. This happens to FWBs, Walthers and Diana recoilless guns made during the 1970s.
Usually, I can pop out an old 124 seal in a few seconds. This one took an hour. Although the top part had disintegrated, the bottom was still fresh and strong and fought me at every point. I finally had to cut it into four sections to pry one of them out.
Took me an hour to cut the old seal up. Hardest replacement I’ve ever encountered.
This is the action fork I mentioned earlier.
Okay, with that much disintegration of the seal, there will be lots of seal parts inside the compression chamber, as indeed there were. Use something sharp and pointy to dig them out of the corners, where they will have impacted over time. I used a patch extractor on the ramrod of my Thompson/Center Hawken. Then, I wrapped paper towels around the end of the rod and soaked them in denatured alcohol to clean the compression chamber. There was no moly there–another indicator that I have never been inside this rifle. Clean until all the seal particles are out and the compression chamber sparkles.
All the oil needs to be cleaned off the baseblock and the action forks. They’ll get a coat of moly grease when they go back together. The pivot bolt will also get a coat of moly, but I’ll describe all that in detail when I tune the rifle.
That’s as far as I will go today.
A shrine built for a Feinwerkbau 124 – Part 2
by B.B. Pelletier
My enshrined 124.
Before we begin, I have to share a laugh with all of you. This is especially for BG_Farmer, who last week had a discussion with me about unloading a muzzleloader.
I was out at the range yesterday and among the guns I shot was my new Thompson/Center Hawken. Of course, the sights were open post and bead. Shot No. 1 went through the X-ring at 50 yards. So, I loaded ball No. 2 very carefully. And, I put a cap on the nipple only after I was in firing position. Then–nothing! The cap fired but nothing else happened.
I waited for about 30 seconds for a hangfire, and then the truth of it hit me. For the first time in 45 years of shooting muzzleloaders, I had failed to put gunpowder into the rifle! So, my status as the Master Doofus of the Universe is, once again, secure–and I have a ball to get out of my barrel. Fortunately, I was using Triple Seven powder, a replica powder that doesn’t attack the bore like black powder.
The first shot from the Hawken muzzleloader went through the X-ring at 50 yards. Shot two is still in the gun.
So, all that talk about how I never had to unload a ball before just went away. BG_Farmer, you may have 12 hours to gather a crowd to mock me.
Now, on to today’s report
Well! This report that I thought would be finished today is turning into quite the crowd-pleaser. Just two days ago, we had a comment from a reader named Simon Kenton who remembers his 124 fondly as being a real tack-driver with the vintage Beeman Silver Jet pellets. He stockpiled 5,000 of them and hates to shoot them because they aren’t available anymore.
I also remember Silver Jets as the best pellets for the 124 back in the 1970s and ’80s. But when I competed in field target with a 124 in the late 1990s, I used the 7.9-grain Crosman Premier, which, at the time, was considered the most accurate pellet in the world. And I’m referring only to the Premiers that come in the brown cardboard box.
So, I’ll test this 124 for accuracy with Silver Jets and Premiers, and perhaps even some JSB Exact 8.4-grain domes. Sorry Kevin, but I don’t seem to have any Beeman FTS. I have Trophys, but that’s all.
Please don’t worry about the status of the gun. If something happens, it’s only an airgun after all. I’ll do everything to protect the exterior finish, but if I have to rebuild the powerplant for any reason, the rifle will only get better as a result. And after I rebuild it, it will last many decades longer than it would have with the original parts. We know that today, but of course it was not known when the 124 was new back in the 1970s.
For the collectors
And I need to clarify a point for all the collectors. I said in the first report that the 124 dated back to 1972, but that isn’t entirely accurate. The basic rifle did exist at that time, but in the United States it was called the F-12. In Germany it was called the model 121. The 124 was first called by that designation in the 1974 edition of the Beeman catalog–the ultra-rare second edition. In that catalog, Beeman explains that the 124 is an upgraded version of the F-12 rifle that previously existed. That probably means the 124 designation started some time in 1973. Yes, there are FWB sport rifles marked as model 121, and yes, they were also capable of velocities up to 780 f.p.s. When the exact upgrades were made that differentiated a 124 from a 121, I do not know; but it sounds like a great research project for some day when I’m tired and just feel like reading.
The .22 rifle
To round out the report, there was a .22 caliber version of the same rifle that was marked as the model 127. They were never as popular when the gun was being made, because in those days .177 caliber was king in the United States. Finding a 127 is more difficult than finding a nice 124. However, for some reason, the price is seldom that much higher. The 124 still holds sway over the 127, even today.
The Beeman R5/model 125
Beeman also had a very small number of 124s barreled in .20 caliber and labeled model 125. It was never an official model, but Robert Beeman was very keen on .20 caliber and was seeking at the time to create an R5 rifle for his line. Beeman remembers three or four of these rifles being built by Feinwerkbau. They were not marked with the R5 designation, though that was the plan once production began.
What stopped the project cold was the requirement to purchase .20 caliber barrels 5,000 at a time. Beeman was prepared to order 500 of the R5s, but he wasn’t ready to commit to 5,000, so the rifle was never built. Two of the prototypes, marked as “Sport 125 Cal.5/.22″ were sold from the Beeman used gun list. The company also advertised the new R5 in their 10th edition catalog; but since there were no guns to sell when that catalog came out, the price was listed as NA. Catalog 10A followed the same year, and the R5 model was removed. Many people who have seen just the 10th edition of the Beeman catalog believe that a Beeman R5 existed, when in fact it never did. Robert Beeman wrote a very detailed description of all that transpired on this project for my magazine, Airgun Revue #3.
Today, I want to show you more of the contents of this sarcophagus. I’ve already discussed why filling the barrel with common grease is not a good protective measure, so let’s look at some other preservation techniques that backfired.
Baggies don’t protect
The orignal owner also felt that Beeman Silver Jets were the best pellet for the rifle. Instead of making a single storage compartment for the square cardboard box the Silver Jets came in, he divided 500 pellets into two plastic bags that were tucked into smaller asymmetric compartments. You can see them in small slots on either side (the top and bottom) of the rifle’s forearm in the case. Unfortunately, he was unaware that plastic bags are not an effective vapor barrier. Over the years, the acid wood gasses corroded all the lead pellets to the point that they’re now covered by a thick coat of white lead oxide powder. These pellets are now useless. I leave them in place as tutorials for whenever I show the rifle.
Beeman Silver Jets came in a square box with a padded styrofoam insert. These pellets are 20-30 years old and not oxidized.
Silver Jets on the left came from the box. The oxidized one on the right came out of one of two baggies inside the gun box.
Another fact the original owner was unaware of is the tendency for the original FWB piston seal material to dry rot. He purchased three spare piston seals that are now, sadly, hardened to the point of uselessness. The plastic bag they’re in also did noting to preserve them. That’s okay, though, because I would never put an original FWB piston seal back into a rifle anyway. I would use something made from modern synthetics. Feinwerkbau wasn’t alone in making this mistake. Diana also used the same flawed material in their target air rifles and pistols of the 1970s, as did Walther.
You don’t have to be an expert to see the damage here. The piston seal is dried and cracked from storage. Each of the three seals has two o-rings. The larger one is the breech seal, but I don’t know where the smaller one goes. These are still usable.
The rest of the inventory
For those who like to keep score, the box contains these things, besides the rifle and owner’s manual:
500 Silver Jet pellets
Beeman deluxe cleaning patches
Can of Birchwood Casey Sheath
Bottle of Beeman Silicone Chamber Oil
Bottle of Beeman Spring Cylinder Oil
Two stainless steel oiling needles
Leather sling
Three-piece sectional cleaning rod
Two .177 brass bore brushes
Beeman Pell Seat
Three piston seals
Three breech seals
One new mainspring
One aluminum trigger blade
None of these products have been used. They are there for “that day” when they are needed.
And, now, the velocity
Or not!
The Crosman Premier pellets refused to come out of the end of the barrel. They went perhaps 7/8 of the way through and stopped. I checked and replaced the breech seal, but no luck. That means the piston seal has finally given up the ghost. The last time I shot this rifle through a chronograph, it registered about 760 f.p.s. with Premier Lites, but that time is past. And the parts in the gun are of no help in fixing the situation.
I left the first part of the blog exactly as I wrote it, so all of this that you are reading has transpired before your eyes. I will now tune the gun with a modern FWB 124 tuneup and then test it for you.
