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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.

 

Well bang went that version of the theory, but after sleeping on it I realized it actually didn't need to wiggle out of

recoil line and return line in order for this event to happen. All that needs to happen is for the bolt to go back too

far--which it is still doing--and for the extractor to be out just far enough to catch the edge. It must have been

something like that. With the, admittedly subjective, finger press weakness you are describing for the extractor

the scenario looks the most likely now. Still a cautionary tale and a very interesting one. Glad your Thompson

receiver wasn't damaged when it happened. We won't see anymore West Hurleys' of that era again. My

recommendations are still replace extractor, replace springs and I would bet Deer Slayer would say the same.

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My full auto WH was hitting the bolt stem as it passed through the hole . Left a burr / displaced metal , though . Filed out the burr and pollished the bolt stem and put a radius on the hole . Think revolver cylinder chambers cut for speed loaders. It can happen with WH quality control .

Chris

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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.

 

CTS,

 

Check your PM's.

 

Joe

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My full auto WH was hitting the bolt stem as it passed through the hole . Left a burr / displaced metal , though . Filed out the burr and pollished the bolt stem and put a radius on the hole . Think revolver cylinder chambers cut for speed loaders. It can happen with WH quality control .

Chris

That sounds like solid advice and insight Chris. Thanks! :)

Edited by T Hound
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Just a random thought.... You might want to put that firing pin somewhere it cannot be found. Unless you have paperwork allowing its possesion of course.

 

 

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.

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Okay. I can now see why you are saying that Z3BD. Can't have a fixed firing pin--at least not along with

the bolt it fits into. CST's doesn't look like it has that possibility though. If it does then it "Possibly" makes

it an open bolt system which, regardless if it is a semi-auto, will classify it as a full-auto. Right. Then again

this is not a problem unless you have the bolt that goes with it. Don't have one with the other or

you could get into legal issues. I don't remember any laws saying you can't have full-auto parts unless

you have all the "ingredients" to assemble a full-auto firearm.

Edited by T Hound
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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.
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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.

 

Hey brother glad to hear it, but I would like to add anyway that I wasn't judging, just trying to add to my knowledge, and I think Big Daddy was just concerned that you should know which obviously you did; but, I wasn't even thinking about it given the interesting gunsmithing

situation you presented. It's all good. :)

Edited by T Hound
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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.

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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.

 

And besides the springs, it looks like someone dremeled or ground out part of the front of your receiver. It was not smooth and appeared to have gouge marks although I cannot be for sure without a more detailed picture. But I am not surprised at all. Good thinking on your part to measure the springs--that didn't even occur to me. I believe that if you get a Kahr bolt--which absolutely should fit into your receiver--then the Kahr springs should work. Kahr sells their bolts for about $160.00. Or you might slighty bore out the West Hurley recoil spring recess cavities.

Edited by T Hound
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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.

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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.

 

So it is not the bolt that is the problem, rather the recoil guide pins? Use Kahr recoil guide then. That is an interesting note for furture reference--the difference between the spring OD and the spring wire diameter. I wonder how many other differences there are between West Hurley and Kahr/Auto-Ordnance?

 

As far as springs go, spring performance depends on a lot of factors such as metal used, diameter, method of manufacture, heat treating. Did you measure the force of the recoil springs and the firing pin spring? Keep in

mind that the firing pin spring also doubles as a recoil spring--it is just not called that.

Edited by T Hound
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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.

 

As far as springs go, spring performance depends on a lot of factors such as metal used, diameter, method of manufacture, heat treating. Did you measure the force of the recoil springs and the firing pin spring? Keep in

mind that the firing pin spring also doubles as a recoil spring--it is just not called that.

 

Guys,

 

If you don't have it already and are working with springs this site will give you pretty much everything you need to know:

 

http://www.planetspr...?id=compression

 

Most springs used in firearms like the Thompson are made from music wire. Allow about .010" dia clearance between the guide / hole and the spring.

 

That "firing pin" / "return" spring on the W/H Kahr is identical to the FA TSMG 1928A1 spring only shorter. Not surprising, since when N/K introduced the semi they had a large stock of FA parts from their purchase of Auto Ordnance.

 

Joe

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Great information Joe, as usual for you! thank you! :D Edited by T Hound
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