light primer striking problem

[painter777]

" a striking problem, but only when the barrel is pointed down"



In this picture below, the rounded tip of the firing pin looks broken off. Like Floyd pointed out it looks like a Flat nose. I wouldn't be surprised to see the slotted area of the Firing pin is wobbled out where it intersects with the stem of the Extractor... Allowing the Firing pin longer travel. Have seen this before.

If you enlarge the OP's last picture of the bolt face... You can also see under the Plunger cone that the extra webbing (below the left side of the Extractor) has a rough/burred area. To me the Primers have a larger diameter impact area, not like a U imprint the spent casings in my hand look like. Maybe this 'Blunt Impact' is in part the reason the Primers are backed out?

If mine, I would swap out the Firing Pin, File away the rough edge on the bolt Web, install a new Extractor, Plunger Spring assembly, and install a new Ejector spring. If the Ejector tip is in good shape and working properly it could stay. But for a few $$ more you could have a rebuilt bolt and change the Ejector tip/spring assembly. Anything still in serviceable condition become extra parts.

I'd be interested in seeing a Macro pic of the current Firing Pin tip.



Pic from a Auction showing Firing Pin Tips:

[floydthecat]

" a striking problem, but only when the barrel is pointed down"

https://www.milsurps.com/attachment....2&d=1624597310

In this picture below, the rounded tip of the firing pin looks broken off. Like Floyd pointed out it looks like a Flat nose. I wouldn't be surprised to see the slotted area of the Firing pin is wobbled out where it intersects with the stem of the Extractor... Allowing the Firing pin longer travel. Have seen this before.

If you enlarge the OP's last picture of the bolt face... You can also see under the Plunger cone that the extra webbing (below the left side of the Extractor) has a rough/burred area. To me the Primers have a larger diameter impact area, not like a U imprint the spent casings in my hand look like. Maybe this 'Blunt Impact' is in part the reason the Primers are backed out?

If mine, I would swap out the Firing Pin, File away the rough edge on the bolt Web, install a new Extractor, Plunger Spring assembly, and install a new Ejector spring. If the Ejector tip is in good shape and working properly it could stay. But for a few $$ more you could have a rebuilt bolt and change the Ejector tip/spring assembly. Anything still in serviceable condition become extra parts.

I'd be interested in seeing a Macro pic of the current Firing Pin tip.

https://www.milsurps.com/attachment....7&d=1624522462

Pic from a Auction showing Firing Pin Tips:

https://www.milsurps.com/images/impo...55939672-1.jpg

To me, it almost looked like pictures of two bolts. A couple shows a possible flat tip, but one for sure looked normal to me. The strikes on the cases OP posted looked just fine to me (the strikes I mean), but as already mentioned, they are the ones that fired.

[USGI]

I'd be interested in seeing a Macro pic of the current Firing Pin tip.

Charlie, click on those in post #23. They go so "macro" you might have trouble finding the firing pin. - Bob

Attachment 118225

[painter777]

Hi GIBob,
I used his last bolt picture from reply #23. To me the Tip looks Flat, not having the rounded point we'd expect. And the Primers look Punched instead of Poked.
Could just be me, but I believe the Firing Pin is the problem or part of it.
I'd rebuild the bolt and file that Webbed edge smooth.
Floyd and Double HH are good at finding the Squeaky Wheel and fixing it. Can't get our hands on all of them. Guess we just wait and see what the OP can figure out.

After just reading the first couple lines, With it acting up with muzzle pointed down had me thinking at first that maybe his Trigger wasn't resetting until I read farther.
Haven't been on in a while, Doc has me at a Activity level of 2 on a 1-10 scale until some test results come in. Naturally it couldn't be worse timing with me trying to finish up the rifle club carbines, some big Maple and Oak trees being removed and me just starting wrapping the eaves and fascia in Aluminum. Damn I'd hate to be busy! More rain next few days so I'll try to catch up on Emails and PM's.... until the Meds say Nap time

[floydthecat]

I made an artisanal test to increase the length of the cases by using stickers for shooting targets.
Barrel pointed down, stickers on the primed case bottom:
1.280 Nothing
1.281 Nothing
1.282 Nothing
1.283 Bang

Gentlemen,
for today I give up ...thank you for your help.

I think we need to revisit this test. In think we still need to ascertain the actual head space. Maybe firing by lengthening the case with these stickers caused it to fire, but unless the primer has been moved closer to the bolt face, I can’t see how this helped. Like already mentioned, firing empty primed cases will usually result in backed-out primers. Long head space can also result in backed-out primers. I don’t think we really know at this point if OP has shown us fired primed empty cases or live rounds.

I just think an accurate head space measurement is in order and the bolt has to be striped for that. Everything else on/in the bolt can be examined as well.

[donki1967]

[QUOTE=flydthecat;501374]To me, it almost looked like pictures of two bolts. A couple shows a possible flat tip, but one for sure looked normal to me.

It's the same bolt, I would like to have a second one for testing in my carbine

[DaveHH]

If I understand it, the Boxer primer has an inside anvil that sticks up and the priming mixture is crushed between the metal cover and that anvil. That FP tip looks like it could just be smashing the whole mechanism. Maybe that's it? When the gun is pointed down, any headspace, normal or excessive is enough to really mess up ignition? Kind of a "stacking tolerance" thing? The tip looks like what I was talking about when I said to look at the tip under a lens. It looks like a beat up, chewed up piece of metal. Funny how they look normal at first glance.

Consider that when these guns were run through their 6,000 round tests, all of them had increased headspace, but some were just cleaned and released for issue. So, maybe excessive headspace isn't such a problem in these carbines? I used to wonder how a long case could blow them up, but a case that is too short is OK? If they headspace on the case mouth with a short case, there should be a lot of headspace, but that extractor holds them against the bolt. In which case, extractor movement becomes critical.

[floydthecat]

I agree that it would be pretty hard to rupture a case in a carbine. The case is fully supported and I think it will stop shooting if head space got too long.

I have some experience with that. I picked-up a pristine Iver Johnson once that spaced at 1.311 but would fire maybe every third time. Primers would back-out on anything that fired. I came up with a bolt to pull the space back in to 1.305 and it shot ever since and was still shooting when I sold it. So, I think the action will continue to safely fire out to at least 1.305-1.306 and maybe a little longer, but it does depend on the firing pin protrusion and brass length also. Head space is the distance from the cartridge base and the bolt face. SAAMI allows a max of .022, which is pretty sloppy. One could use longer cases and keep the space within .022 and be in spec. if the headspace was long.

[floydthecat]

I hope we are not drifting OP’s thread too far, but most of this is pertinent to the case I think.

I had a few firing pins in the bin and picked up a bolt just to measure protrusion variations in a particular bolt. I took an I-I, RI and an RI c and measured protrusion of each. It ranged from .055 to .065 among these three pins. .010 can make a huge difference in whether a carbine will fire or not, especially if it is a little long on head space, or the brass is on the short end of spec. All firing pins are not created equal.

[donki1967]

"I hope we are not drifting OP’s thread too far, "
sorry for my ignorance, but what does OP mean?