Carbine slam fire

[Chris W.]

I think they might both ( Winchesters ) might be late. 5,760,78X and 5,761,79X. The first shows no sign of rebuild or rework of any kind, flat bolt, no bayo lug. Second is a BA rebuild with round bolt, bayo lug, M2 stock. Only changes I personaly have done to both is replaced both main springs because the originals measured just under 10" long, out of mil spec. ( should be 10 1/4" long + ) New main springs measure 10 3/4" long, I watched as the two I bought were removed from a stock GI bulk bag.
Chris

[Tuna]

If they are USGI springs I would not worry about them. They are not the cause of the problem. An over sensitive primer can happen and is the most likely cause of the discharge. In all the many thousands of rounds I have reloaded over the years I had one go off while seating it in a case and as I was not expecting it I can say it was a big surprise when it fired. All of the rest of the primers in the package were normal and there were no further problems.

[joem]

I had one go off while priming like Tuina. Super sensitive primers do happen but not ofter, I hope.

[Johnny in Texas]

I have used Rem. magnum primers for all my 7.62 and 5.56 reloading and never had one pop when I did not want it to. They are considered a harder primer but have never had an FTF either. An old benchrest shooter told me that was all he used because the cup is thicker and less likely to rupture.

[Chris W.]

Several tests this afternoon. First, used LC-72 ball rounds, dimple on these the same as the handloaded CCI primed cases. Second, switched back to the short main springs, same result, don't think it's the main spring throwing the bolt harder is the answer. Third, put 200 primed cases through, with the new springs, no slam fires. Fourth, ran 50 cases through twice to see if hitting the primer twice would matter, it didn't, no slam fires out of that lot either. The Underwood did exactly the same dimples. Thinking at this point, it was most likely a overly sensitive primer that caused the AD. That is food for thought as well though, all of the primers I've used to prime the 2000 cases to load used the same lot # of CCI. Guess there isn't much that can be done with that one except to fire these cases and replace the primers with something else next time. Of course the kids will be closely supervised while this is going on until we get rid of this lot. Storage can will get marked appropriately in case I'm not around. Kids will also get properly cautioned and trained each and every time out. The thing I fear most is that with a full mag, the bolt is released putting the carbine into full auto until the mag is empty. But this looks highly unlikely. Still considering dumping the whole lot into a bucket of water and starting from scratch. Hate any accidental discharge, and I feel lucky this happened in my hands, not theirs. Bucket of water might end up being the answer.
Chris

[Tuna]

Chris I think your worrying about nothing in this case. IF another primer should slam fire and that is unlikely the rest won't follow and empty the magazine. As I said in the case I had there was only the one sensitive primer in the whole bunch. It's not something that makes the whole lot bad. Just one out of millions that gets a little bit too much compound in it or the cup is too thin when it was made. As long as your cases have no high primers in them you should be good to go.

[Chris W.]

And I also beleave this to be the case. The only concern is that there are more of these sensitive primers in this lot. With the testing, was unable to find any more so far, no more slam fires. I prime with a lee hand primer, and primers get looked at twice and tested on a surface plate. before they go through the dillon 550 for a powder charge, bullet and crimp. Don't use the dillon to size, or prime because I have found that M1 carbine and .223 for that matter, always need a trim after firing. I don't run a M1 carbine round like I would run a 38 spcl or a 45 acp through the dillon because of the required trim. Still haven't decided what to do with these primed cases yet. Primers are hard to come by these days, but grandkids are a much bigger issue.
Chris

[BlitzKrieg]

On active duty, we did not have slam fires in M1, M14, and the M1/M2 carbine but its becoming obvious, these weapons in civilian hands
produce this malfunction. Poor reloading techniques account for most instances, single round loading .. maybe and may be not. Gunk
encrusted bolts most likely.
No offense but ..... if you have not done a detailed cleaning of the bolt, you are heading to a slam fire at some point and if you don't inspect
reloads for deeply seated primers, you are at risk of a slam fire.

[Chris W.]

No offense taken. But in this case bolts detail stripped all the way down, very lite oil, and very little at that. No poor reloading techniques, just sensitive primers, and it could end up being just that 1 primer. Oh, and by the way, these carbines, and a Underwood mark the primers the same way with my reloads or US GI ball. ( LC-72 ) All of this after inspecting primer seating twice. Has to have been a sensitive primer. The reason for posting this thread and the good discussion fellow CSP members, was to make people realize that this CAN happen, and to watch out for it. After being in the military, I know that some of the worse maintenance happens there when the property doesn't belong to you. Us civilian owners often take much better care of gear after their service than they ever got during. But, that said, single round loading without a mag, guilty as charged