M1 Carbine intermittent light firing pin hits

[greer]

I have an Inland carbine in the shop that may fire the first shot fine showing a good hit on the primer and then barely mark the primer on the next. The bolt seems to be locking in fine and the extractor seems to be snapping over the cartridge rim o.K. The rifle came in with a broken extractor which I replaced. I also replaced the hammer spring and recoil spring and the firing pin seems fine. One fellow said his carbine did the same thing with commercial ammo and shot the gov surplus fine. I'm using commercial ammo while testing this rifle. The fact that it sometimes puts a very good dent in the primer is puzzling. I would appreaciate any advice on the problem.  Thanks alot. greer

[Mike357mag]

I hope your not useing wolf ammo if so try the cheap federal or winchsters, I think they would have a softer primer than any military round or wollf ammo.  It sounds like it may not be closeing all the way when cycled from firing and the hammer is useing most of its energy to push the bolt closed all they way.  Is it possible the ejector is setting forward some, do you have another ejector you can try?  Also you might try putting everything back original except the extractor just to remove possibile new parts problem.

Mike H

[greer]

Mike, Thanks for the response. The ammo I have been trying in it is Winchester. I will look at the ejector although I don't have a spare one. I have left a message with the owner to see if this is a problem it had along with the broken extractor or if it just started after I put the new one in. The bolt not closing completly would make more sense as far as it sometimes putting a good dent in the primer and sometimes barely leaving a mark.  Thanks again for your help.    greer

[Mikey]

greer - have a gunsmith thoroughly dismantle and clean the bolt.  If there is crud buildup in the firing pin channel or under the extractor, or if there are weak springs under either, you will have misfires and light primer dents.  Most of the military surplus sites like Gun Parts Corp, SAMCO or SARCO should have replacements if you need them.  HTH.  Mikey.

[greer]

 This has turned out to be one of the most stuborn problems I've had with a gun. After replacing the hammer spring, recoil spring, cleaning the bolt and firing pin channel, checking the firing pin protrusion (.063), checking head space, and using a couple of brands of commercial ammo this Inland carbine still will make a good dent in the primer one time and then barely nick the primer the next. I guess I'll relace the firing pin although I would think that the light hits would be more consistent if the firing pin was short or defective. As I posted earlier the rifle was brought in because  it was not extracting and it did have a broken extractor. I replaced the extractor and while test firing it would mostly fire the first round and then usually snap on the second so I replaced the mentioned parts. I took the ejector out and it still does the same thing. Whats is also frustrating is the customer won't return my calls to see if it had the snapping problem before I put the new extractor in. Hopefully he is just out of town and will call eventually. The extractor seems to be working fine and is snapping over the rim O.K. The bolt seems to be rotating fully into lockup on a live round . One thing I did notice is that the bolt lacked a little locking up on a go gauge but like I said seems to lock up fine on a cartridge. It has become an almost humourus ordeal. If anyone else has any ideas I would love to hear them. I've not had much experience  with the M1 Carbine in my little gunsmith shop. Thanks for listening.  Greer

[Mikey]

If the bolt fully rotates on live rounds but doesn't always detonate and does not always lock-up on a no-go guage you probably have a headspace problem.  The bolt should rotate, lock up and extract consistently on the guage.  The ammo proably has slightly different specs. 

The carbines had a number of different style bolts and if this one isn't matching it may have been replaced previously and may need replacing again to provide for proper headspace.  HTH.  Good luck.  Mikey.

[greer]

 Mikey,
 Thanks alot. I need to talk to the owner and find out whiich problem started when. I could cut the existing chamber a hair deeper with a pull through reamer but I'll talk to the owner first.  Thanks again. greer

[Mikey]

Rather than re-cut the chamber you may just need to open the bolt face a hair.  Mikey.

[greer]

Yep, that would be simpler, that might be the next thing I do. All this mess aside, I was impressed at how simple a design the carbine is. All this has been a good lesson anyway. Thanks again for your time. greer

[targshooter]

greer,
In the 1970s I used to tinker with the M1 Carbine quite a bit. I have seen the very problem you are describing many times. Usually the following will correct this problem.
     Dissemble the carbine and thoroughly clean it. Pay special attention to the return spring and its housing on the right side of the receiver. Inspect the spring , spring guide and housing. Early carbines will have a tube housing which can be removed from the receiver. This is not as robust as the later housing machined into the receiver. Burrs, dings or kinks have to be addressed. If the op return spring looks worn or is excessivley kinked, replace it. Assemble the rifle. Now you can be assured the bolt is going into battery properly and thus the hammer is delivering its hits correctly on the firing pin.
    Assemble and test fire the firearm.
I had carbine firing pins wear out and become too short. Additionally, I had a carbine that slamfired because the pin was too long. The firing pin is good as long as its not broken (never had this) and of the proper length. Usually, length is the key to determining the firing pin status.
A tired (too many dry firings) bolt can actually sometimes have the firing pin hole peened outward and thus influence the headspacing. I never saw this, but an WW2 armorer told me this was possible.
My 2 cents, but I think this will help you fix it. There was an adage, when in doubt, replace the op spring.
Here is a site you may like:
http://www.geocities.com/buckrodgrs/M1/TB_23-7-1/Cover.html

[greer]

Targshooter,
  Thanks. That spring along with the hammer spring was one of the first things I did. I will check the spring housing. The bolt seems to close smartly and rotate fully into lockup on a cartridge. Like I said I thought it odd that the bolt would not close on a go gauge, especially an older model like this one. Do you know the minimum length for the firing pin? I didn't see that spec in the little manual I have. But again sometimes it will put a good dent in the primer and fire the round fine. Thanks again.  greer

[targshooter]

greer,
I do not have any of the armorer's references I used to have. Still have the gas piston wrench though. Try googling. Fulton Armory used to offer refurbished carbines, perhaps they would share the firing pin dimensions. Is the barrel projection over the receiver threads galled or damaged? Did you check out the op rod? They can do strange things if the bolt lug raceway is galled or if they have been bent. How about the bolt lug, any galling? I once had one that had an out of spec bolt that liked to break extractors. New bolt fixed that. Many of the wartime contractors were not arms manufacturers. Sometimes carbines were just not put together right and they did things like breaking parts and never quite working right. I had pretty good luck with Inland Division carbines, had my worst luck with Postal Meter versions. The government actually cancelled some contracts because of the inability of the supplier to assemble working and accurate carbines. There's my $.02.

[greer]

 I just talked to the owner and he said it has had this problem since he owned it. He got it from the fellow who packed it in WWII. The felow said he luckily didn't have to use it much. That at least tells me it's not the new extractor. I think I'll face off the bolt about .002. I'll let you know how things turn out. Thanks.  greer

[coyotejoe]

Are you absolutely sure the light hits are only intermittent?  I've seen the same thing in revolvers. The rounds that fire will have a deep indent because the pressure forces the primer back over the firing pin, those that misfire show only a slight dent. Check it with empty cases and primers well soaked with WD-40 to kill them, I suspect you may find the firing pin strikes are always marginal.

[greer]

After talking with the owner finally and finding out it had been doing this all along I chucked the bolt up in the lathe and took .003 off the bolt face and what do you know, it fired the whole magazinefull of rounds. Like Mikey mentioned,  it was a headspace problem( not enough). I believe the rifle had this problem from the day it left the factory. The bolt was not locking up on some rounds although it sure looked like it was.  I guess it was at the point where the variation in case length was enough to sometimes let it lock up sometimes and sometimes not. I'll shoot it some more tomorrow just to make sure but it seems to be cured. I've sure learned a few things about M1 Carbines. Thanks alot to everyone for the help, I sure appreaciate it.  greer