Posts Tagged ‘disassembly’
by Tom Gaylord, a.k.a. B.B. Pelletier
My rifle is actually a BSA Super Meteor.
The last report on this BSA Super Meteor was on October 15. That’s how long it’s been since we saw this gun in print. But in the background, I’ve been doing lots of things that I’ll share with you today.
The last time we looked at this rifle, I was taking it apart and getting a lesson on how it was built and what was wrong with it. To summarize for you, this BSA Meteor is made from folded metal, in the same way Daisy BB guns are made. And the piston head was attached to the piston by means of an E-type circlip that was incapable of standing up to the stress. I can tell that by the damage that was done when that clip let go — but more because the Brits have invented a much better solution for fixing this gun today, when it does break down — and all of them are going to break!
I sent my order to T.R. Robb in the UK for a replacement piston head, o-rings and spacers. The problem is that when I sent in that order I didn’t pay attention to the fact that the same order button also got a piston head for a BSA Scorpion pistol, which is larger than the Meteor head. Well, guess which one Mr. Lysdexic ordered?
That’s right, I ordered the Scorpion piston head. And a couple days later, when I realized what I’d done and contacted T.R. Robb, they had already shipped the order. But to their credit, they sent a second piston head — this one was for a Scorpion, too. That’s right! They sent me 2 Scorpion piston heads and no Meteor head! But I’ll give them credit for trying to help me, for being very generous and refusing my offer to pay for the second head, and for being very prompt in shipping both heads. I had them in less than 10 days.
So, blog reader David Enoch — I now have a spare BSA Scorpion piston head that I believe you said you needed. The price will be right, too. You’ll pay what I paid, which was nothing.
Lots to see here. The replacement piston head is the shiny one on the left, the darker original is on the right. Obviously, the replacement part is larger and has to be cut down to fit. The blue spacer and 2 o-rings are just some of the soft parts that came in the kit. There were a total of 4 o-rings of different sizes and 2 more spacers of varying thicknesses. They allow you to set the power of your airgun, and they also allow for differences in the tolerances of different guns.
When I saw how large the piston head was, I knew it wouldn’t fit. I asked my friend Otho to cut it down for me on his lathe. He also had to cut the o-ring channel deeper at the same time.
Silly me — I thought that would solve everything. So, Otho took the head and had it back to me in a week. Then, I assembled it to the end of the piston and tried to insert the piston back into the spring tube. But it wouldn’t fit! I’d taken it out several weeks earlier, and now it wouldn’t fit back inside! It was like that pair of blue jeans that used to fit, before they suddenly and quite mysteriously shrank. I hate it when that happens — especially to jeans I’ve worn for years!
I took a more critical look at both the spring tube and the piston. Glory be — they’re both made of folded metal like a Red Ryder! Except that Red Ryder spring tubes are generally round, while both of these pieces had variable shapes, with a tendency toward the oval.
The tail end of the piston. Here you clearly see that it’s folded metal, tack-welded at each end.
At least that’s the theory! Here you see the weld at the piston head end has broken. Wonder why the piston is no longer round?
And, on the other side of the piston, opposite the broken weld, the solid metal has also cracked! Here you can see the nut that now holds the piston head to the piston body. It’s not about to break off like the circlip did!
Looking at just the condition of the piston gives you an idea of the shape this rifle is in. I don’t think the design of the rifle caused all this damage. I think people continued to try to cock and fire it after the piston head separated from the piston, and they hammered it into the mess you see here.
I examined the interior of the spring tube very critically at this point and found a lot of metal galling (shiny areas that indicate the scraping of metal against metal without lubrication). There was also a fair bit of surface rust. I also found that some of the folded metal edges of the spring tube that hold the trigger parts were bent into the interior of the spring tube and were blocking the passage of the piston. I fixed those with a Dremel tool, but the inside of the tube was too deep to reach.
I showed the spring tube and piston to Otho, who agreed with me as to the extent of the damage. He felt he might be able to clean out the tube with a tool that holds strips of abrasive paper and is spun in an electric drill. I don’t own that tool, so I was only too happy to let him have a go at it. He also said he could tack-weld and refinish the piston where it was separating.
So, Otho came to the rescue once more. And he was true to his word, because a week later I got back the tube and piston, ready for assembly. But that wasn’t the end of the rifle’s problems!
Otho welded the broken piston and dressed it round again.
Otho also welded the back side of the piston where it was cracked.
Loose barrel pivot
I had discovered that the barrel wobbled from side to side when I first got the rifle. And a little research online told me this is a common problem with Meteors from the 1970s. Apparently, when the forearm stock screws are tightened, the shape of the stock allows them to pull apart the action forks that hold the barrel breech. It’s a design flaw of the rifle, and the solution is to not over-tighten those screws. But how to fix it — since the barrel pivot is a pin, rather than a bolt? Well, this is something I know how to do.
I chucked the forks in the padded jaws of my bench vice and closed the jaws on the forks. When there was some inward tension on them, I hit the outside vice jaw with a 2-lb. ball-peen hammer, which sent a shock wave into the metal of the action forks and realigned their crystalline structure. Or at least that looks cool when I write it. I haven’t got a clue what really happens! All I know for sure is that when you do this, the metal takes a set in the new position, and now the action forks are about 5 thousandths of an inch smaller then the breechblock of the barrel that has to fit between them.
Finally, all the faults had been corrected, as far as I knew. The piston now slides into the spring tube with only a little friction, not unlike a Weihrauch piston in a Weihrauch gun. It was time to assemble the rifle!
Otho and I both think whoever designed this Super Meteor Mark IV was a genius at eliminating cost and making one thing do many jobs. The way this air rifle is designed should be a study in an engineering course, but the students would first have to know how others had done the same things with other spring-piston powerplants. At every turn, you can see the embodiment of the Spartan design.
And the parts that need to be hard are hard! I mean glass-hard! There’s no wear on any of the trigger parts, or on the piston, where it’s held by the sear. The boys at BSA knew what they were doing.
Since there had been so much metal galling in the spring tube, I first lubricated it with Moly Paste before any parts went back in. The molybdenum disulphide particles will bond with the metal surfaces and will not wash out over time. I applied this paste (which is a thick grease) with a swab made from a long thin dowel rod covered with a paper towel on one end.
This simple swab can be used to clean the inside of spring tubes/compression chambers, as well as to lubricate them.
After the inside of the spring/compression tube was lubricated, I also lubricated the outside of the piston head and piston tail with the same moly paste. I’d like to say a word about the piston head now. The kit of parts I was sent had 3 spacers of differing thicknesses. Any of them will work, but each gives you a piston head of a different length when it ‘s fastened to the piston body.
The way the Meteor is designed, adjusting the length of the piston head controls the power of the rifle. A shorter piston head will give a longer piston stroke and therefore greater power. I don’t want power. I want a smooth rifle that’s easy to cock and is also easy to shoot. So I went with a thicker spacer on the head.
Now, I lubricated both the piston head and the tail with moly. The center of the piston body can be left dry because it’s narrower than the ends and will never touch the inside of the spring tube.
The piston head is lubed with moly paste. No precision is required for this application because this stuff spreads as the gun is cocked and fired. The other end of the piston got the same treatment before it was slid back into the spring tube.
Once the piston was in the tube, I coated the mainspring with Beeman Spring Gel and slid it into place inside the piston. Don’t look for that product anywhere — it’s obsolete. It was a viscous silicone (Beeman only says it’s a synthetic in their catalog; but given where it’s going, I’m pretty sure it’s silicone) grease that dampened vibration without slowing the gun much, if any. So, pretty much any viscous silicone with the consistency of toothpaste should suffice. Or, you could do it the old-school way and just use a lithium-based grease.
The powerplant went together the same way it came apart; but the barrel, which was the next item, was harder to install because the action forks were now smaller, thanks to my repair. Nevertheless, the barrel did go into the action forks of the spring tube (I “buttoned” it in using the baseblock to spread the forks slightly), with the cocking link locked inside the piston and lots of moly grease on all metal surfaces that touch.
When it came time to close the barrel, I got a small surprise. It seems the spring-loaded chisel detent (the chisel-looking thingie that holds the barrel shut when the gun fires) was sticking out so far that the barrel wouldn’t close! Examination revealed that the detent is held in the baseblock by the pivot pin that passes through. How in the heck was I going to do that?
Well, if you think like a redneck cheapskate, which I am trained to do, you insert the pivot pin partway, lever the chisel detent back as far as it will go and then tap the pivot pin home. I could have closed my eyes for this maneuver, it went so smoothly. Obviously, I’d discovered something that the original 28-year-old BSA assembler, Trevor, could do 175 times in an 8-hour shift back in 1978.
From there, the only big task was to get the mainspring back inside the spring tube all the way. It only stuck out the end of the tube less than an inch, but it also had to go another full inch into the tube, where it would be held by a crosspin that’s profiled on one side to capture the base of the spring guide. It’s easier to just show you.
This is the side of the assembly pin that fits inside the base of the mainspring guide and holds it inside the rifle.
This 58-cent tool was made from a 4-inch plastic sprinkler pipe in about 20 minutes. With the action in the mainspring compressor, it pushes the washer at the base of the mainspring, while allowing the crosspin to be inserted through its slot. It isn’t beautiful, but it worked both times I used it and looks like it will hold up for dozens more jobs like this.
And the pin is back in place. The contours on the other side of the pin have meshed with the base of the spring guide.
I showed you these parts and the trigger parts in the earlier reports, namely in Parts 2 and 3. So I’m covering ground that I’ve already explained. When I took the rifle apart back in October, I didn’t have to use a mainspring compressor; but to get the mainspring back in place and insert the crosspin, I did. And it was easy.
And the remainder of the airgun went together exactly as it should. I have a theory. Whenever something goes together easily, it means I’ve left out something. I’m in my wetsuit but have forgotten to put on my briefs! I remember learning how to disassemble and assemble the M1 Garand rifle. I thought I could never learn, but a few weeks later I was stripping it like a pro. That’s the way BSA spring rifles are, I guess. You’d like them to come apart in 30 seconds without hand tools, but they don’t. However, once you’ve been down the path a few times, I’m sure the job seems simple.
This is the part I dreaded. Sure the parts were back together, but who was to say they were where they should be? Only cocking and firing the gun would tell me that. So I did. And it did! Hurrah!
The only task left to do is to clean the barrel. I had close to 2 months to do that while it was off the rifle; but to tell the truth, I wasn’t sure if I would be able to get the gun back to functioning again. No sense doing a great job on a barrel I’ll never use. But now the gun is working, so the next report can be about the velocity.
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.