CTS

That's an instant bookmark! Thanks

Actually the Kahr and WH springs have the exact same OD. The difference is wire gauge. The .006 smaller wire of the original springs makes the ID .012 larger. I was looking at spring weight comparisons. I was surprised that the recoil springs each have more "rate" than the much larger firing pin spring. Larger OD and larger wire diameter makes for a spring with about half the force. Isn't bigger always supposed to be better? Learn something new every day.

I'm beginning to think this issue is the result of a combination of errors. If I had to guess, someone had been tinkering with with it prior to me and I think they lacked a basic understanding of physics and mechanics. The recoil springs measure 7.5", several inches shorter than the springs I just received from Kahr. Looking at them you can see where they were cut. The Kahr springs, by the way, don't fit my West Hurley. The Kahr's are .037 wire and the one's in mine are .031. I also noticed that when cocked, the last 3/4" of bolt travel was very soft. I'm thinking the spring was cut in some misguided effort to lessen cocking resistance. I recall now when it originally jammed I did get a ruptured case. I'm going to try some different weight recoil and firing pin springs as well as some Sorbothane buffers in various thicknesses.

It is a fixed firing pin. On the standard pin, since it floats, when it retracts, the tab on the bottom engages the trigger mechanism and "cocks" the rifle. Since this is fixed, when it retracts, it holds the bolt open. Or at least that's what I surmise. I didn't attempt it before disposing of it.

Yes. It's not in my possession. Thanks, though. I can't tell you how often I run across people walking around with questionable if not absolutely verboten hardware- likle at gun shows.

Bolt is 1.046 and bolt cavity is 1.057 so 0.011 clearance cold. Lateral movement on the bolt face is very small. Clearance for the extractor is quite large through the groove broached in the bore of the receiver. The bolt moves freely when forcibly skewed and there's a moderate radius on the inside of the hole that the bolt passes through. If there's been any modification done inside, it's not apparent. All the machining marks are consistent and it has very little bluing scuffing. It's very unlikely that it's not the original finish based on appearance. I've looked at this thing from every conceivable angle and tried to force the extractor to do what it did. I have had no success in duplicating the problem. The only thing I can figure is that the extractor is down on spring tension. I reinstalled it in the bolt and laid it next to the spare. Doing the highly-scientific "push on it with my finger" test, the one that jammed doesn't feel as strong. I ordered several extractors so I'm going to try that. I also have some high-durometer Sorbothane on the way and am going to experiment with springs. i contacted Deerslayer and he's no longer selling his spring/buffer kit. I know I'll piss away $80 worth of time but I have a tough time coughing up that much for 30 cents worth f plastic and $8 worth of springs.

This is the bolt in place and retracted and then completely assembled. I can pull the bolt as far back when fully assembled as shown without the springs. I would think that if the design relied on spring stack to limit travel, the springs wouldn't last long at all. It would quickly deform the coils. Also, the springs have very little compression on them with the bolt closed. I've worked on racing engines for decades and I've always pulled rocker arms for long layups for the reason you cite. I've never seen a spring lose strength unless stored in compression. Plus, these springs are relatively linear in load resistance. In other words, they take about the same effort to compress through virtually all of their travel. So new springs will compress just the same as these, given that their minimum compressed length is less than the clearance in the travel path. The net of this is I can't imagine the design relies on the spring to be the limiter of maximum travel. I'm curious about your observation that something looks "different" in here. I'm interested to know if these new pics show you anything. I have a friend that has a Kahr. I may have to go and borrow it tomorrow and take a peek inside.

The position of the bolt in the receiver as shown in the first photo is the bolt with the recoil spring guide installed and retracted all the way. Where you see it now is without any springs, but I put springs in and the travel is the same. If it weren't, the springs would be damaged if they coil-bound before the bolt contacted the guide in its most rearward position. So if I'm not missing any parts, and as you say the bolt shouldn't be retracting that far, what am I missing?

Bolt in receiver "Special tool" Extractor position when jammed Note: Rounded corner on extractor

The face in front of the extractor's claw is still blued and a little shiny on the part that pops over the cartridge base. It fits very tight in the bolt- no different than the spare I have. The spot on the retention tab doesn't look deliberate- it's just one corner and maybe .005". I put the bolt back in and have been moving it incrementally, looking for anything and I still see nothing. There is a groove cut in the receiver where the extractor area of the bolt passes through the "block". Lots of clearance and no burrs. I PM'ed the gentleman that sells the buffer and spring kits. I haven't heard back yet, but I'm going to give that a try. Since I have to order pins and ejectors, I'm going to order a new set of stock weight springs as well. I'll play with the variables and see where it goes. Either it was a freak occurrence and won't ever happen again, or it will continue until something breaks and I find out what it is. I'd prefer the former. If it's the latter, I'll report back. Is there a better source for these parts than Kahr, or "better" parts available? The "tool" was pretty simple. I took a small flat blade screwdriver and gently bent a curve into the 1st inch of the blade. I ground the inside to provide clearance. Looking at the bolt in the receiver, the extractor sits at about 11 o'clock. This went around the bolt and under the stuck extractor. I was able to slip in between the retention tab and the extractor hook. I tied the bolt back all the way, wrapping cord around the rear site and the bolt handle and positioned the barreled receiver muzzle down on a pad. Gripping the receiver in my left hand, I positioned the screwdriver and wedged it in. I held it between my 3rd and 4th finger and positioned a punch driving downward between my index and middle finger. It took a couple good whacks to pop the extractor back into position. It would have been much easier with a helping hand. I'll try to get a pic tonight. I Googled repeatedly and found no reference to this ever happening with a Thompson.

Serial number is 1629P. It's an A5. Looking at other S/N's it appears to be a 1979. This is the odd thing- not only is the extractor not broken, it's not even bent. It still has the inward curve to it. The only thing I notice is that the tab on the underside that keeps it in place appears to have one corner that looks like it was touched on a grinder. There's no way I would not replace it though. On the bolt, it's going much further back than you describe. It retracts past the opening and into the rear cavity by about an eighth or three-sixteenths. I don't see how this would be a problem as, like I wrote earlier, I can't fathom how the extractor would move outward that far. (even though it did) At the same time, I see no reason for it to travel that far and that means there's plenty of room for a buffer pad. On the springs, this thing appears to have been very sparsely used. Maybe a hundred rounds, if that. So that probably eliminates springs. In fact, if the springs were any heavier, firing this thing would be a two man operation. Plus, aren't lighter springs a recommended approach? I suppose I can write this one off to a freak occurrence- and maybe a mis-ground tab on the extractor. And extractors aren't that expensive. And now that I have a tool and a technique, if it happens again it's not a big deal. The biggest concern is damaging the bolt. Time to add a brass hammer and a pin punch to the range bag.

What I meant by "missing part" was- "did the AO production 1927 have a buffer?" I would like to know why this jam happened and how to prevent it from happening again. As I mentioned, i wondered why the bolt would retract so far into the receiver to allow the extractor to hang up as it did. I also am very curious to know how the extractor became dislodged. In thinking it through, the only time the extractor would be deflected would be sometime between when a round was stripped from the mag and when the bolt went into battery. On the way back out I don't imagine the ejector would push the extractor out much, if at all. So, this is my confusion- not seeing a buffer in the parts diagram for my 1927, but having this failure and the idea that the bolt travels so far rearward. I looked at the referenced page- the buffer I have looks to be the same one shown in the M1 diagram all the way at the bottom. I attached the parts diagram I am working from- downloaded from the AO/Kahr website.

Yes, extractor, not ejector. Mondays... In the case of my jam, the extractor did move rearwards (towards the bolt body). Looking at the extractor slot, there's a round hole slightly behind the bolt face thatthe retention tab on the underside of the extractor engages. Then there's a T-slot that terminates in a round hole. On the spare bolt, the rear of the extractor aligns with the end of the t-slot right at the hole. On mine, the extractor was pushed back into this round cutout. I had to tie the bolt handle to the rear site, then make a tool that I could slide around the curvature of the bolt and slide between the bolt body and the space between the extractor tip and the position retention tab. I then braced it and drove the extractor forward with a pin punch. It snapped back down into proper position and I was then able to remove the springs, guide and then the bolt. I found that the firing pin retainer pin was sheared and that the pin that limits firing pin forward travel was almost sheared. I looked at both the manual and parts diagram downloads on the AO website. The parts diagram shows what looks like a 1928 and shows a U-shaped buffer (listed as M1 part), The "manual" shows the 1927 and does not show a buffer. I am wondering if there's a part missing. While it doesn't show or list a buffer, I can't help but wonder why the bolt would be able to withdraw past the opening in the receiver and if the movement of the extarctor wasn't related to the bolt coming to a violent halt while traveling rearward. FYI- I only fired the rifle on one occasion and the jam occurred within 10 rounds.

I questioned the buffer issue as one is not indicated in the AO/Kahr parts schematic. I inquired about the Tommygunner spring and buffer kit. I was told it was available only to gunsmiths. On these buffers I have, I put one in the press and with 5k/lbs on it, the deflection was .003". On the recoil spring out the back, I should have noted- this is the steel receiver. They are three-hole bolts. This whole issue began with a bolt jam. The bolt retracted rearward and the ejector somehow became dislodged. It moved rearwards in it's retention groove. The tab on the inside face held the ejector out and away from the slot and hung up on the hole between the bolt cavity and the magazine well. It was a real head-scratcher figuring out how to get the whole thing apart. I ended up having to make a tool. Thanks for your insights!

What's your opinion on the buffers? Are buffers even useful or are they only a necessary addition when loweing recoil spring tension? These are exceptionally well made, but as rigid as they are I question if they have much absorbtion ability, if any. I'm also curious as to why two thicknesses. The way these are constructed leads me to wonder if they're not a commercial product that has just come and gone.

The round thing is a flat head socket capscrew that was in the bag. I meant to lay it sideways. I don't see anywhere it could be used on the gun. The pin is for affixing whatever sort of firing pin that is. The firing pin's profile is such that it would not have been cut from an original piece. As it is pinned into the bolt in a fixed position it essentially makes the bolt the same as an open bolt in functionality. That being said, I have no idea how it would actually function relative to engaging with the trigger group. Not that I have any intention of trying. I have been researching buffers and I have not run across any that look like this. The one's I've seen are one-piece urethane cutouts. These seem to lack any "give" that a urethane piece would have so I wonder what purpose they would serve. I neglected to note that they are a different thicknesses. One at .290" and the other at .400". That would seem to indicate they either had a different effect based on thickness or that different versions of the rifle required different sizes. I'd be curious to know if anyone knew anything specific about them. To the best of my knowledge these parts have been in this box for the last 30 years or so. As far as the bolt, is it wise to hang onto a spare? It seems to me to be the only piece that would be hard to replace or repair. I also have gotten the impression that bolts of current manufacture are of lesser quality.

I recently came across these parts which came with a 1927A5 I acquired a few years back. I believe it to be a 1979 West Hurley. The one I know is a replacement bolt. The other one appears to me to be some sort of fixed firing pin. Its pin location positions it to where the tip slightly protrudes through the bolt. I believe the two U-shaped pieces to be some sort of buffer. Their shape appears to be close if not identical to the aftermarket buffers I have seen. They are a sandwich construction with the two outer plates rivited together with a hard plastic in the center. I have not attempted to compress it but by probing it seems to be almost rigid. The plates appear to be stainless and the edges are all nicely machined radii. Any information would be appreciated.