nw00738 Posted April 9, 2014 Report Share Posted April 9, 2014 (edited) Hi everyone,I picked up my Thompson yesterday and fired it today. I had 5 failures to feed and then the rifle ran 100% for the remaining 145 rounds. I did however notice that a few of my casings had pierced primers. I load them myself, and since it was a new rifle I tried minimum charge. Is it possible to install the hammer wrong to cause this or any other step in field strip? Here is the brass that had the piercings. I measured the firing pin protrusion(not sure I have done this correctly). I wanted to refer to my owners manual, but apparently I was given one for an M1 Carbine Here is my rifle just for grins. Thanks for any insight. Edited April 10, 2014 by nw00738 Link to comment Share on other sites More sharing options...
T Hound Posted April 9, 2014 Report Share Posted April 9, 2014 (edited) The protrusion in the semi-auto should only be .045 inch to .055 inch--aim for .050 inch. 0.089 is indeed a bit excessive. Begging your pardon, but getting the M1 Carbine instead of the Thompson manual is hilarious. Edited April 9, 2014 by T Hound Link to comment Share on other sites More sharing options...
nw00738 Posted April 9, 2014 Author Report Share Posted April 9, 2014 The protrusion in the semi-auto should only be .045 inch to .055 inch--aim for .050 inch. 0.089 is indeed a bit excessive. Begging your pardon, but getting the M1 Carbine instead of the Thompson manual is hilarious.I got a kick out of that too. Thank-you for the info. Do you know if the firing pin can just be shortened? I am curious if the metal is hardened below the surface. If not I guess i'll be calling Kahr and ask them to send me a new one. Link to comment Share on other sites More sharing options...
T Hound Posted April 9, 2014 Report Share Posted April 9, 2014 (edited) To answer your question--no you shouldn't shorten your firing pin. The reason is due to ATF regulations. You see, the firing pin has another function other than to detonate the primer. The firing pin also is designed to pin the cartridge against the feed ramp should the semi-auto disconnector fail. This is by design and ATF regulations in order to prevent full-auto function. Shortening the pin could defeat this failsafe and get you in legal hot water. Here is what does need to be done: Perform a Go/No Go test using Go/No Go gauges that you can buy from Brownells or other firearm gunsmithing retailers for about $25.00. This will tell you if things are in specification. After that you should check your firing pin type for the correct one. Kahr sells two types of firing pin, one long and one short. Maybe they somehow put the wrong firing pin type in your model. It is not inconceivable given their track record lately. what is the particular Kahr model for yours--TM1, T1, etc? I can shoot an inquiry email to them to see. per your question about installation of the firing pin. The firing pin slides back and forth between two holding pins which keep it from going out of range. If you forget to put in the forward pin I suppose it is possible it would go too far except that the very end of the firing pin will prevent it. There is a ridge near the end which has a greater diameter than the portion which goes through the firing pin hole. It is stopped there before the firing pin portion that would strike the pin actually reaches the forward holding pin. but something bothers me here. You only had five failures to feed and the other 145 fired with a five deeply dented cartridges. I am not sure you actually have a problem. I would have thought that the pin would have stopped the cartridge from going in if it was too long. This being a new gun it is possible that the firing pin spring is just strong. Overtime it will lessen. If the gun is firing with no other issues then it is probably just a matter of breaking the gun in. Edited April 9, 2014 by T Hound Link to comment Share on other sites More sharing options...
nw00738 Posted April 9, 2014 Author Report Share Posted April 9, 2014 Thankyou for saving me from a big mistake, my model is a T1B50D Link to comment Share on other sites More sharing options...
T Hound Posted April 9, 2014 Report Share Posted April 9, 2014 (edited) No problem brother; but, also, see my update about the firing pin in my previous post. Give Kahr a day or two to answer my inquiry and then I will update with a post in this thread. I amgoing to ask them what the protrusion should be for your model. Edited April 9, 2014 by T Hound Link to comment Share on other sites More sharing options...
Paladin601 Posted April 9, 2014 Report Share Posted April 9, 2014 To answer your question--no you shouldn't shorten your firing pin. The reason is due to ATF regulations. You see, the firing pin has another function other than to detonate the primer. The firing pin also is designed to pin the cartridge against the feed ramp should the semi-auto disconnector fail. This is by design and ATF regulations in order to prevent full-auto function. Shortening the pin could defeat this failsafe and get you in legal hot water. Here is what does need to be done: Perform a Go/No Go test using Go/No Go gauges that you can buy from Brownells or other firearm gunsmithing retailers for about $25.00. This will tell you if things are in specification. After that you should check your firing pin type for the correct one. Kahr sells two types of firing pin, one long and one short. Maybe they somehow put the wrong firing pin type in your model. It is not inconceivable given their track record lately. what is the particular Kahr model for yours--TM1, T1, etc? I can shoot an inquiry email to them to see. per your question about installation of the firing pin. The firing pin slides back and forth between two holding pins which keep it from going out of range. If you forget to put in the forward pin I suppose it is possible it would go too far except that the very end of the firing pin will prevent it. There is a ridge near the end which has a greater diameter than the portion which goes through the firing pin hole. It is stopped there before the firing pin portion that would strike the pin actually reaches the forward holding pin. but something bothers me here. You only had five failures to feed and the other 145 fired with a five deeply dented cartridges. I am not sure you actually have a problem. I would have thought that the pin would have stopped the cartridge from going in if it was too long. This being a new gun it is possible that the firing pin spring is just strong. Overtime it will lessen. If the gun is firing with no other issues then it is probably just a matter of breaking the gun in.great question, shouldn't the dimensions of the complete firing pin be checked? Also I would use the Depth gage at the other end of the caliper for measuring protrusion ( it is the rod that sticks out as you open up the gage jaws Link to comment Share on other sites More sharing options...
T Hound Posted April 9, 2014 Report Share Posted April 9, 2014 (edited) Good point Paladin. Thanks. Update: I measured my spare Kahr-Thompson bolt with installed firing pin and theprotrusion reading came out to be 0.088 inches which is not far off 0.089. Thatjust leads me to believe that there is probably no issue that further breaking-in won'tcure. Nevertheless I already shot off an email to Kahr Tech. We will see, hopefully,what they have to say. The protrusion figures of 0.45 to 0.55 were figures I got from other forum membersa few years ago--yeah, I keep Thompson gunsmithing information on record--so what?LOL! But let's see what Kahr says. Edited April 9, 2014 by T Hound Link to comment Share on other sites More sharing options...
T Hound Posted April 9, 2014 Report Share Posted April 9, 2014 Here is Kahr's answer to my inquiry: (apparently the paste function on this site is not working for me) Okay here is what Matt McKeon of Kahr wrote: Our gunsmiths want to see it and you should send it in. In other words, they ignored my request for what the protrusion should be. I'llkeep trying. Link to comment Share on other sites More sharing options...
nw00738 Posted April 9, 2014 Author Report Share Posted April 9, 2014 (edited) Well thanks for trying. I think I will try a few more rounds through it and see if it goes away. I'll keep an eye on the firing pin and bolt face to make sure there is no damage. It happened about 3 times in the first magazine and the last few happened over the course of the 3 boxes of ammo I fired. The more I think about it, the firing pin spring being too strong/new seems like a solid theory. Here are a few of the other rounds. Edited April 9, 2014 by nw00738 Link to comment Share on other sites More sharing options...
emmagee1917 Posted April 9, 2014 Report Share Posted April 9, 2014 Another thought is that the primers you're reloading with may be too thin/weak in the cup material . Whatcha using ?Chris Link to comment Share on other sites More sharing options...
Paladin601 Posted April 9, 2014 Report Share Posted April 9, 2014 (edited) Kahr is covering there butt, they want the part in their hands before they make a statement, or they could just swap the part. Sounds like Lawyer talking. Edited April 9, 2014 by Paladin601 Link to comment Share on other sites More sharing options...
T Hound Posted April 10, 2014 Report Share Posted April 10, 2014 So far they have not replied back to my second email asking if they can at leasttell me if the protrusion is within specification. So, yeah you are probably rightabout them trying to cover their butt. Emmagee, I thought about that too. Cheap primers with thin walls--but that seems less likely becauseof the safety issues with weaker walled primers. But it could be---especially if they are foreign made. Link to comment Share on other sites More sharing options...
T Hound Posted April 10, 2014 Report Share Posted April 10, 2014 Okay, I did some research on the Kahr Tommy Gun shop site and found out that theyno longer, apparently, offer the short tip fiiring pin although the long tip firing pin picturesstill show the little inset blow up of the tip in order to identify it. Therefore ALL of therifles AND the Thompson pistols use the long tip firing pin. So be advised, the problemis probably not due to firing pin tip type--the short tip would be obvious anyway since itprobably wouldn't even dent the primer. Link to comment Share on other sites More sharing options...
nw00738 Posted April 10, 2014 Author Report Share Posted April 10, 2014 (edited) I fired factory ammo today, Winchester white box 230 with the same result. I will call them tomorrow to discuss options.For the record I am using Winchester primers. Edited April 10, 2014 by nw00738 Link to comment Share on other sites More sharing options...
T Hound Posted April 10, 2014 Report Share Posted April 10, 2014 If they give an explanation, let us know. Link to comment Share on other sites More sharing options...
nw00738 Posted April 10, 2014 Author Report Share Posted April 10, 2014 If they give an explanation, let us know.I will do that. Thanks again for your efforts. Link to comment Share on other sites More sharing options...
Paladin601 Posted April 10, 2014 Report Share Posted April 10, 2014 The problem is probably not the primers. Winchester are usually very good primers. , Some say high pressure other a firing pin problem. I found this on another web sight, it said a few strokes with a file solved the problem ( sorry, it would not allow me to copy/paste What load are you using? I believe you want to be around 850 fps. Also what crimp are you using, a roll crimp or taper crimp? I prefer a taper crimp myself, has less tendency to build excessive pressure. and lastly, are the cases with the pierced primers raised some above the case base? If so, it is a little of both. The pressure is pushing the primer out of the pocket and into the firing pin, piercing it. Hope this helps Link to comment Share on other sites More sharing options...
nw00738 Posted April 10, 2014 Author Report Share Posted April 10, 2014 (edited) The problem is probably not the primers. Winchester are usually very good primers. , Some say high pressure other a firing pin problem. I found this on another web sight, it said a few strokes with a file solved the problem ( sorry, it would not allow me to copy/paste What load are you using? I believe you want to be around 850 fps. Also what crimp are you using, a roll crimp or taper crimp? I prefer a taper crimp myself, has less tendency to build excessive pressure. and lastly, are the cases with the pierced primers raised some above the case base? If so, it is a little of both. The pressure is pushing the primer out of the pocket and into the firing pin, piercing it. Hope this helpsI am using 4.4 grains of red dot, I was using 4.9(I use this in my 1911) when I first posted. I decided to drop it even further to see if that was it . My manual says max for that load is 5.5 and has my loading @ 715 fps(add about 100 for the 16.5 bbl). I am using a taper crimp I believe (rcbs dies). This happened on the factory ammo as well today. Hopefully kahr will have some answers. Thanks for the response, i'm trying to narrow it down so every suggestion helps. Edited April 10, 2014 by nw00738 Link to comment Share on other sites More sharing options...
Paladin601 Posted April 10, 2014 Report Share Posted April 10, 2014 (edited) sounds like you are doing everything right to fix the problem. How do you like Red Dot, I bought some because I could not get Unique Edited April 10, 2014 by Paladin601 Link to comment Share on other sites More sharing options...
nw00738 Posted April 10, 2014 Author Report Share Posted April 10, 2014 It is very smoky, but seems to work well. Link to comment Share on other sites More sharing options...
T Hound Posted April 10, 2014 Report Share Posted April 10, 2014 Got a second reply back:Quote: I do not know the measurement you are looking for. Our gunsmiths have informed me thatthe pierced primers are due to a combination of issues which they can take care of. We candefinitely send you a replacement firing pin if you would like. Any service not performed byour gunsmiths will void the warranty. Thanks, Matt McKeonKahr Arms/Auto Ordnance130 Goddard Memorial DriveWorcester, MA 01603Email address: service@kahr.comPhone: (508) 795-3913 Unqoute. If he can talk to his gunsmiths--who are just next door--then why can't heask about the dimension? I think we know the answer. Link to comment Share on other sites More sharing options...
Paladin601 Posted April 10, 2014 Report Share Posted April 10, 2014 If it is under warrantee let them deal with it. Could also me an overly machined firing pin pocket. If that is the case the bolt face may be thinner that specs. Please correct me if my thinking is off tract. Link to comment Share on other sites More sharing options...
emmagee1917 Posted April 10, 2014 Report Share Posted April 10, 2014 I have seen cases where excessive headspace caused , or was a factor in , pierced primers .No pun intended.Chris Link to comment Share on other sites More sharing options...
nw00738 Posted April 10, 2014 Author Report Share Posted April 10, 2014 (edited) I decided to be stubborn and try one more time. I put 50 rounds of Winchester white box through it with no issues. After that I tried my hand loads once more. Not one issue with them. No pierced primers in 150 rounds. I'm thinking/hoping this was a break in issue? Possibly overpowered springs? Edited April 10, 2014 by nw00738 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now