Posts Tagged ‘disassembly’
by Tom Gaylord, a.k.a. B.B. Pelletier
This report is getting long and perhaps a little confusing, so let me explain what I’m doing. We’ve been looking at the Air Arms TX200 Mark III underlever air rifle. I used my own TX for the first 6 parts of the report. In Part 7, I introduced a brand new TX that Pyramyd Air sent for me to test. Many of you were concerned that the rifle had changed somehow over the years since mine was made, and perhaps what’s shipped today isn’t the same rifle…so I agreed to test a new one for you. The first look at that rifle came in Part 7 of the report, and in Part 8 we looked at the velocity.
Today ,I’m going to show you the trigger in detail, describe how to adjust it and explain why I always say the TX trigger is an upgrade of the Rekord trigger that Weihrauch introduced back in the 1950s. To get to the trigger adjustments, the triggerguard must be removed. But today I’m going farther into the gun to show you the entire trigger assembly. That will help me explain how the trigger functions.
The stock needs to come off to get into the rifle, so I did that first. Just remove 2 forearm screws and 2 more triggerguard screws.
Once out of the stock, the action and trigger can be seen clearly.
Here you see the disassembly bolt (all the way to the lef). Turn it out, and the rifle comes apart. You can also see the 3 trigger adjustment screws. On the trigger blade are screws to adjust the first-stage length and adjust the sear contact area. Behind the trigger blade is an Allen screw that adjusts the trigger pull weight. Behind that is the threaded hole the rear triggerguard screw goes into.
If I were just adjusting the trigger I wouldn’t need to go even this far. Just remove the triggerguard and start by adjusting the trigger return spring tension. I found that was all I needed to do on the test rifle, as the first-stage length and sear contact area were right as they came from the factory. But you can adjust either of them or both.
To take the trigger unit out of the gun, I removed the disassembly bolt. As it turned, I pressed down on the entire barrelled action with the end cap resting on a soft cloth pad. When the bolt was free, the mainspring decompressed less than 2 inches.
When the trigger unit comes out of the rifle, it’s still pinned to the end cap and spring guide like this. Now, the trigger unit looks familiar to Rekord owners because the 2 pins that hold it to the end cap are visible.
Because I want to show you how this trigger works, I’m going to continue to disassemble the end cap. The 2 pins that hold the trigger unit in the cap are driven out. They are several times harder to remove than Weihrauch trigger pins. This unit is together very tight!
Once the trigger assembly is out, we can see how it differs from the Rekord.
The trigger assembly is similar to the Rekord — but also different. The box is riveted together instead of being a folded sheet metal structure. There’s an additional pin, forward of the trigger blade, and internally there are bearings where the Rekord parts just turn on pins.
So far, I’ve shown you the differences but not described how they work. For starters, the Air Arms trigger has adjustments for the first-stage pull and for the sear contact area, as well as for trigger-pull weight. The Rekord has the sear engagement adjustment and the pull weight adjustment but not the first-stage adjustment. But that isn’t what makes the Air Arms trigger better.
What makes the Air Arms trigger better is the presence of bearings instead of just pins. The parts are also more finely fitted, which has to be done during manufacture because there’s no money in the gun for costly hand-fitting. And the trigger isn’t the only place that’s different. The piston is also different.
The TX200 has what I will call a circular piston. All pistons are circular, of course, but most of them are held from rotating by the cocking shoe. Because of that, the piston can have a hook that’s engaged by the trigger when the gun’s cocked. That’s how the Weihrauch rifles that use the Rekord trigger are made. But what if the piston was free to rotate on its axis?
Blog reader RidgeRunner asked how the TX piston was cocked by the sliding compression chamber. The answer is that the chamber pushes the piston back until the trigger catches it. The piston rod is so long that it can be caught by the trigger while the piston is still inside the compression chamber.
When the gun is cocked, the piston rod comes back and pushes the trigger parts into lockup. As they lock up, a hook catches the rear of the piston rod and holds it until the sear releases it.
The ability of the piston to turn on its long axis while being supported front and rear by bearings adds smoothness to the powerplant without sacrificing power. A centrally located air transfer port that’s centered on the piston boosts the air scavenging efficiency and therefore the available power. The TX200 Mark III is giving all the power it can from a powerplant that’s still smooth and easily cocked.
How is the trigger after adjustment?
Before I adjusted the trigger, it released crisply at 1 lb., 12 oz., which is 28 oz. All I adjusted was the trigger return spring tension and now the trigger breaks cleanly at 12 ounces. So the adjustment dropped one entire pound. And, yet, the sear still has the same contact area, so it’s just as safe as before.
A good tuner can adjust a Rekord just as light, but the sear contact area won’t be as great as it is at 3 lbs. The Air Arms trigger allows for this adjustment without sacrificing any safety. That’s what I meant by the TX trigger being more finely adjustable that a Rekord.
By the way, the work done here, including taking the pictures, took a total of 30 minutes.
by Tom Gaylord, a.k.a. B.B. Pelletier
My rifle is actually a BSA Super Meteor.
Today I’ll tell you the rest of the story. And, what a story it is! I had no plans for this part of the BSA Meteor report to go as long as it did. Circumstances just led me to this point. All I did was faithfully chronicle what happened.
When we left the Meteor yesterday, I’d removed the piston body, but the piston head was still stuck inside the spring tube in the forward part we call the compression chamber. The best access is through the air transfer port — a hole 0.125 inches in diameter. I had a pin punch that fit the hole, and I hoped it would need only a couple taps to come loose, but it was far tighter than I’d thought. The pin punch went in as far as it would go (about 1.5 inches), and the head was still out of reach from the other end. I needed a longer punch.
The air transfer port provided the best way to get to the stuck piston head. With the barrel removed, it was easy to insert a pin punch through the hole and tap the piston head out of the compression chamber.
I flipped the spring tube straight up, with the transfer port on the lower end, and poured Kroil (penetrating oil) on it to loosen the head. This is similar to freeing a stuck piston in an old tractor, except that this is smaller and a lot easier to work on. I left the Kroil in the spring tube overnight; and by the next morning, none had passed the piston head. The piston was stuck tight!
My shooting partner, Otho, made me a 12-inch pin punch from music wire that was exactly 0.125 inches in diameter. I met him out at the rifle range, where he gave me the new punch. All it took was a couple taps with a ball peen hammer and the head came right out. The Kroil on the walls of the spring tube made removal that much easier once the head got to the place where the oil covered the walls.
What came out of the gun was surprising, as it didn’t look like a Meteor piston head was supposed to look. But it did appear to be factory-made. Experience has taught me to, “Make haste slowly,” as Benjamin Franklin once said, so I studied the piston head and thought about the project for a day.
Looking on the internet, I found one other person who had the same problem — the head separating from the piston. And his gun was filthy dirty inside, just like this one. When he described his piston head, it turned out to be exactly like the one in my gun and also is not a head that’s normally seen in a Meteor. Then a happy thing happened.
New blog reader Dag Evert told me my rifle looks like a blend of different Marks to him. He sees some Mark IV and some Mark V characteristics in my gun, and he told me that he has seen 3 different piston heads in these rifles. For some reason, the guy on the internet thought someone had substituted a BSA Scorpion piston head in his rifle.
The piston head of a normal Mark IV Meteor has a large o-ring near the front of the head that is backed by a buffer washer. The head is either keyed to a slot in the end of the piston or there’s the newer (cheaper) kind of piston head that’s held on the piston by an E-type circlip. That kind can separate from the piston just like mine did.
My piston head appeared to have leather around the sides. I had to destroy the leather material to find out if I’m right about the composition, but I also don’t care for the weak way this head attaches to the piston. According to what I’ve read, it’s actually very weak! I would like to replace it with a new piston that uses a more conventional head that won’t separate from the piston while inside the gun.
This is what the Meteor piston head looked like when it came from the rifle. This is an enlarged and enhanced photo, so you can see the separation of the o-ring and buffer washer; but when looked at in normal light at normal size, this head looked like the sides were all leather. The shallow groove in the end of the head is for the E-type circlip that holds it fast to the piston.
This is an E-type circlip that’s used to hold the piston head to the Meteor piston.
John Knibbs in the UK has an entire rebuilt piston with a new head that’s ready to go, but the price is 45 British pounds, which is about $72.00. Add shipping to that, and it comes out to around $80 — which is more than the rifle cost. Of course, I have to either fix the rifle or sell it for parts, and I do want to fix it. So, I’m going to have to spend some money. I don’t want to make parts for this gun if I can get around it…because most of our readers can’t make parts, either.
I kept searching for something that was less expensive. I had a perfectly good piston, so all I needed was a new piston head. Instead of being attached with a circlip, as mine is, I wanted one that had a more positive attachment so it wouldn’t separate again.
At this point, I wasn’t entirely sure that the head in my gun was the same as what was being offered on the internet. It was time to take my piston head apart, and that probably meant destroying the soft parts. But since this head wasn’t going back in the rifle again, I saw it as no loss.
The first step was to remove the rear washer behind the buffer material. It should have been free to come off, and it was.
Whatever material the buffer washer was made of, it was completely gone by this time. The simple act of pulling off the metal washer behind it caused the washer to begin to disintegrate. It wasn’t the leather I thought it was.
The o-ring was so flattened by years of compression inside the chamber that it looked like something else. I cut it off to show that it is really a conventional o-ring.
With the o-ring cut off, you can see that this piston head is the usual one found on a Meteor. But the method of attachment to the piston by a single circlip is far too weak for reliable operation.
What I needed was a piston head with all the parts that attached to the piston with something more positive than just a circlip. And with more searching on the internet I found what I needed. On T.R. Robb’s website, I found an adjustable piston head for BSA Meteors that comes with the buffer washer, 2 o-rings and a nut to fasten the head to the piston.
Best of all, the cost for this piston head shipped to the U.S. is just 17.25 British pounds, which is only $27.51. That’s affordable in my book. I ordered one, and hopefully it’s on it’s way.
The fact that such a piston head exists tells me that others have had this same problem. That, by itself, is reassuring to know.
Before I end today’s report I want to draw your attention to the old piston head once more. Notice that the top of the head is bare metal. That’s the part that rests against the end of the compression chamber. But it doesn’t slam against it — or at least it’s not supposed to. If it did, it would hammer the gun apart in a relatively short time.
No, the compressed air in front of the piston head cushions the head from striking the top of the compression chamber when the gun is working right. Hopefully, all that’s needed to get this rifle working right again is a new piston head with fresh seals and some cleaning and lubrication of the gun’s other parts.
by Tom Gaylord, a.k.a. B.B. Pelletier
My rifle is actually a BSA Super Meteor.
It would be an understatement to say there was a lot of interest in the BSA Super Meteor I got at the Roanoke airgun show. And in the discussion that followed, I learned a lot about this rifle that is now in its seventh design iteration.
First of all, the experts agree that the Meteors — Marks I and II and possibly the Mark III — are the best ones. Certainly, both I and II are. My Mark IV, on the other hand, is characteristic of BSA’s lowest days, when quality went out the window — at least to hear some readers tell it.
I don’t have a Mark I or II to compare with, so all my observations have to be based on this one gun. When I tried to fire it for the first time, it sounded horrible — as if it was broken.
Well, it turns out that it was broken! Today, I’ll show you the step-by-step process of disassembling this air rifle, and I’ll finish the story tomorrow with the damage I found and what I intend doing about it.
I’ve never liked disassembling BSA and Webley spring rifles because of how they go together. I suppose that if I did it all the time, it would seem simple; but compared to a Weihrauch, Air Arms or even a Diana, these two brands seem to be harder to separate. They seem to be designed for production — not for maintenance. At least, that’s my impression.
Having said that, however, I was surprised how easily this rifle did come apart. It was very straightforward and never gave me a bit of trouble. Like I said — I don’t have as much experience disassembling BSAs or Webleys.
All my photography today was done with a flash, so please excuse the poor exposures of some of the parts. I’ve made sure you can see what’s important, and I’ll direct your attention to it in the text…but these are not as good as my normal photos.
Step 1. Remove the stock
The stock comes off with two screws on the forearm and one on the triggerguard. Once out of the stock, it was easy to see why the forearm screws had pulled apart the action forks. They’re screwed directly into them instead of being attached farther back on the spring tube. This is a weakness in the design. Also, each screw was missing a stock spacer that keeps it from pulling on the action forks.
The forearm screws attach directly to the action forks. When they’re screwed tight, they tend to pull the forks apart — especially when they’re missing their spacers. Note the barrel pivot pin above the flange with the threaded hole.
When I removed the stock, I could finally see the trigger adjustment screw. It obviously adjusts the sear contact area, so be very careful when you adjust it!
With the action out of the stock, you gain access to the trigger adjustment screw.
Step 2. Remove the trigger parts
In the Meteor, the trigger housing is welded to the spring tube. So, it stays on the rifle, but the trigger parts have to come out to remove the piston, which is held by the sear on its side, rather than with a center rod. The trigger parts are held inside the housing by 2 pins, although it looks like 3 pins at first. One of those pins is a rivet and does not come out of the gun.
Trigger parts are held in by only 2 pins. The small pin above the curved trigger blade is pushed out from left to right, releasing the blade; then, the large silver pin at the top left is pushed out to release the rest of the trigger parts. The rivet at the right side of the housing stays where it is.
Normally, when faced with pins like these, I get a pin punch set, but I found that the trigger blade pin was loose enough to remove with just finger pressure, alone, and the large silver pin came out by pushing on it with a combination of my finger and a ballpoint pen! The large silver pin in my rifle appears to be a captive pin that remains with the trigger housing. The trigger was completely dry, which surprised me because it came apart so easily.
You have to take the trigger parts out because they’re being pushed up by the trigger spring to block the piston. The trigger pushes on the sear, which bears on the edge of the piston, so it has to be removed to allow the piston to clear the spring tube.
Once the large silver pin is removed, you can pull the trigger parts out of the housing. They consist of the trigger blade and the sear, plus a bent spring that puts upward pressure on the sear when the parts are pinned inside the trigger housing. The trigger blade contains the adjustment screw plus nylon bearings on both sides to keep it from wobbling when installed. It’s more sophisticated than it looks from the outside of the gun. Also, I can tell by the minimal wear patterns that both the trigger blade and the sear are at least surface-hardened. My guess is that they’re case-hardened.
The trigger parts consist of the sear, trigger blade and trigger spring. The pin shown here is the same one that was removed to take the trigger blade from the housing. The white oval on the trigger is a nylon bearing that takes up any side-to-side wobble, plus it helps hold the adjustment screw in place.
Here’s the trigger housing with the parts removed. The large silver pin appears to be captive in my rifle. You can also see the rivet that never comes out. Notice how dry the mainspring is!
I noticed how very dry all the parts were. I was beginning to suspect that this gun had never been apart since it left the factory. Of course, without a complete disassembly, it was impossible to tell for sure; but I would have expected to find some lubrication on some parts. At this point, there was no lubrication on anything, and all the of the parts were dry, dusty and lightly corroded.
Step 3. Remove the mainspring retention pin and the mainspring
Step 3 is where you can make a very big mistake. With many airguns, the one or two cross pins on the side of the spring tube hold the mainspring and its guide in the rifle. The Meteor has a single pin, but it isn’t held in the rifle in the same way that other cross pins are held. Instead, this single pin is keyed to the spring guide. If you try to drive it out with a pin punch, you’ll ruin the pin and probably ruin the spring tube as well.
Here you can see the mainspring retention pin. Its function is similar to all retention pins in other spring-piston air rifles, but this one has a secret. It’s keyed into the spring guide. Until you take tension off the spring, this pin cannot be taken out of the rifle. If you try to take it out with a pin punch before taking tension off the mainspring, you can damage parts.
To get the pin out, you must take spring tension off it by pressing the mainspring in and away from the pin, then press the pin out of the gun from left to right. It will press out with finger pressure just as easily as the trigger pins did, once the spring tension is taken off. You need to make a special tool to take off the spring tension. I was able to make this tool with a part I bought at a local hardware store for less than 60 cents.
The tool does not have to be strong. It only has to put about 90 to 110 lbs. of force on the spring guide. I had my choice of steel, aluminum or plastic parts to work with, and I chose plastic so it would be easier to work. I bought a 4-inch PVC pipe riser made for a yard sprinkler system. I knew this would be easy to work with a Dremel tool. I brought it home, measured the work to be done and made the cuts on the pipe with an abrasive wheel. The total work time was about 20 minutes. I now had a tool that would span the cross pin and push on the base of the mainspring guide.
In about 20 minutes, I made a tool from a 4-inch sprinkler PVC pipe. It isn’t beautiful, but it worked the first time and looks like it’ll hold up for dozens more jobs like this.
I’d intended to use the spring compressor with this tool; but after I saw how easily it worked, I decided I could use it outside the compressor. All I did was put the tool around the pin and pressed down on the barreled action, taking all the spring tension off the pin. It was then very easy to press the pin out of the gun with just my finger.
Here you can see how the cross pin is retained by the base of the spring guide. You can also see the small amount of tension that’s on the mainspring of this rifle when the pin is installed. It was easy to take the cross pin out and take the tension off the mainspring without a compressor.
Then, I could remove the mainspring and spring guide from the rifle. Once they were out, I saw there was no lubrication on any of these parts, nor was there any on the inside of the rifle. I was pretty certain at this point that the rifle had never been apart; or, if it had, that someone had intentionally dried off every part before assembly.
The mainspring looks pretty good. I rolled it on the table and couldn’t see any significant canting. I believe I’ll use this mainspring when the rifle’s rebuilt.
The mainspring looks pretty good, but it’s bone dry.
Step 4. Remove the barrel
It was time to take out the piston. On this gun, the piston is connected to the cocking linkage in such a way that the barrel has to first be removed from the spring tube to disengage the cocking linkage from the side of the piston. The Meteor has a pin (instead of a bolt) as a barrel pivot. Like all the other pins on this rifle, this pin was only tight enough to hold the parts in position. I could move it with my finger. I broke the barrel open to take all tension off the pin (from the detent), then pushed it out from left to the right.
The barrel pivot pin has been started by finger pressure, alone. No pin in this rifle has needed a pin punch for removal. To get the pin all the way out requires a push from a screwdriver.
With the pin out, the barrel pulls away from the spring tube, and the cocking link can be removed from the piston. The piston can now be removed from the rifle.
Step 5. Remove the piston
Once the cocking link is out of the piston, it’s time to slide the piston out of the spring tube. Everything was so dry on this rifle that the piston had to be coaxed out of the gun by levering it with screwdrivers through the cocking slot. When it was out of the gun, I discovered that the piston head wasn’t attached! It’s still inside the tube at this point! No wonder the gun fired so violently!
The piston is missing its head. It passes through the hole on the end of the piston and is held in place by a circlip, which is missing.
That would normally be all you have to do to strip a Meteor, but I still have to get the piston head out of the gun. I suspect it’s going to tell me a lot about why the gun failed like it did.
This is turning into a long report, so I’ll finish it tomorrow.
by Tom Gaylord, a.k.a. B.B. Pelletier
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.
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.
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!
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.
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.
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.
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.
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.
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.
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.
by B.B. Pelletier
Is this Custom Match the best HW 55 ever made? Read the report to find out.
In the last report, I tuned the rifle and got rid of the objectionable firing cycle. It’s always a great pleasure to return to a classic air rifle like this one after testing so many modern airguns, because these oldies are so reserved and well-behaved. I know it’s not going to kick, roar and fight me at every turn. It may only be suited to shoot 10-meter target, but sometimes — and by that I really mean often — that’s exactly what I need.
I had to remove the sights during the tuneup, so the rifle needed to be sighted-in again. It wasn’t that far off, but the indices are so dark on a 55 rear sight and my eyes are so bad that I had to play around until I discovered which way to adjust the sight to go right. In this respect, a modern 10-meter rifle has it all over a vintage one.
The first pellet I tried was the H&N Finale Match Rifle pellet. I haven’t had a lot of recent success with this pellet in target rifles, but in the past this was one of two to contend with — the RWS R-10 Match Pistol pellet being the other. This time was different, though. Although the first group wasn’t what I wanted, it showed enough promise that I shot a second and a third. By the third group, I could tell this pellet likes this rifle.
Next, I tried the RWS R-10 Match Pistol pellet, and I gave it the same number of chances, but it never showed me anything. That was a surprise, because I think this pellet is one of the more accurate pellets in several of my other 10-meter rifles.
Following the R-10, I tried the RWS Hobby pellet, because in my HW 55 SF — the 55 that has no barrel lock — Hobbys do surprisingly well. Again, there was no joy this time. I’m showing the group to contrast with the others in this report.
At this point, I was satisfied that this rifle is accurate, though it won’t give an FWB 300S any competition. But why stop there?
I next mistakenly loaded some obsolete and nondescript European diabolos that I mistook for JSB S-100 competition pellets. Boy! If you ever wanted to see a comparison between good pellets and cheap ones in a good gun, this was it! How about a three-quarter-inch five-shot group?
Back to serious ammo. The next pellet I tried was the H&N Match Pistol. This is not a Finale Match pellet, and I find that these sometimes vary in weight a lot more than Finales tend to, but there can be surprises. Not this time, though. The best group looked like Hobbys. Oh, well!
After that, I tried H&N Match Rifle pellets. They’re the same as Match Pistol, only heavier. But for some reason that nobody understands but everybody believes, they shot great! These are the pellets for this rifle — until I find something better.
The rifle is shooting fine with the new tune. I could live with less power, but what I have isn’t bad. The trigger is a joy, because it breaks at just 7 oz., and that’s as light as I need it to be. Shooting from a bench in the rested position doesn’t give you the full feeling of the rifle. All it shows is the potential for accuracy, and this one’s got it.