Failure to fire - Light Primer Strikes?

[JEFFPPC]

Brass problem!! (headspace) Too short, gets pushed forward in the chamber and you get FTF! See if your fired brass will "rechamber with no resistance". If so, neck size and reload. Start there!!

Right church, wrong pew. Your bumping your shoulders to far.

 

[LVLAaron]

I would sure encourage you to get a new pin from Kelbly's. Actually, a good move would be to buy a firing pin assy...the one you have now would be a good spare. I've got a plastic container full of spares...it's saved my bacon a time or two.

I keep a spare full assembly, and trigger, for each of my comp guns in my range bag... Agreed. It will save you one day, or a friend.

 

[LVLAaron]

What would bumping shoulders have to do with a FTF ?

hot dog down a hall way syndrome.

 

[JMA]

A good way to check a firing pin is to drop a #2 Pencil down the bore and hold the barrel straight up in the air, Many times on a shorter barrel it will actually fly up out of the barrel, But on a long barrel, Use a flashlight and depress the trigger it should fly up the barrel quite far if it has a good hit like it should. It only works on barrel it will fit in though.

On a 1911 it will throw the pencil up in the air if everything is working like it should.

After reading this I just had to try it. got a couple of my 1911's out.
One of them, when held a little above waist hieght actually bounced the pencil off the cieling.

 

[NorCalMikie]

What would bumping shoulders have to do with a FTF ?

Push the shoulder back TOO FAR, firing pin pushes the shorter case forward in the chamber, just enough that you get a soft strike. (or FTF)
You need to start somewhere and that's as good a place as any.
If you pull the bullet out a bit so you get a longer OAL and "a jam into the lands", that will hold the case head against the bolt face.
Once that round is fired and the case is fire formed to the chamber and the shoulder is pushed forward, make sure you don't bump the shoulder too far back and end up with the same thing all over again.
Better yet, see if the fired case will rechamber with little to no resistance.
If so, neck size, prime, reload and go shooting. Don't move that brass any more than needed.

 

[gunsandgunsmithing]

I’m not really on board with the theory, I’ve shot some very short cases with zero problems. With the extractor holding the case to the bolt face coupled with a spring loaded ejector applying opposite force, I just can’t picture how a case is moved forward by a firing pin causing a FTF.
I don’t have x ray vision to observe a chamber during combustion of course nor am I a gun builder, rather just a common sense approach.
Firing pin drag or weak spring may produce a FtF idk but not extra headspace.
Maybe I’m wrong, maybe I’m right..

It happens...seen it many times, especially with new brass that typically runs on the small side. As NorCalMikie said, it "softens" the blow. Primers need a hard, fast hit and anything that allows it to move just a little, softens the blow. Lots of times, just a softer primer is all it takes. A hard primer, like a cci 450 does it more than say a fed 205m. Once the case is fireformed, problem gone.

 

[Sniperhandle]

I’m not really on board with the theory, I’ve shot some very short cases with zero problems. With the extractor holding the case to the bolt face coupled with a spring loaded ejector applying opposite force, I just can’t picture how a case is moved forward by a firing pin causing a FTF.
I don’t have x ray vision to observe a chamber during combustion of course nor am I a gun builder, rather just a common sense approach.
Firing pin drag or weak spring may produce a FtF idk but not extra headspace.
Maybe I’m wrong, maybe I’m right..

Excessive headspace is a known issue that will cause misfires. I'm not talking about 3 or 4 thou.

 

[gunsandgunsmithing]

Excessive headspace is a known issue that will cause misfires. I'm not talking about 3 or 4 thou.

Yes, I've seen new brass that was around .015 short. No big deal once it's properly fireformed but that's enough, especially with hard primers. I find that most fire but a few just won't.

 

[Uncle Bruce]

I was able to straighten the pin that I dropped and bent. It was bent about 3/4” from the tip, so I could straighten it out pretty easy. Once I straightened out the pin, I assembled the bolt without the spring and sure enough there was quite a bit of drag in the last 1/8” of travel. I coated the end of the pin with sharpie and cycled it and found two high spots. I polished the pin some then lapped the pin in the firing pin hole using JB bore paste. That did the trick. The firing pin now shakes freely too and fro, really smoothly. I’m pretty sure that will solve the problem.

I really appreciate the kind words, the ideas and encouragement! Without your posts, I wouldn’t have had the courage to take the bolt apart and lap the firing pin. I learned a lot tonight.




Al, you were correct! That’s exactly what I did (put sharpie on the pin tip and found two high spots) and I think I found the culprit.

I’m not sure I’ll be able to get to the range during the week, but I may just prime some empty cases and see if I can shoot 50 or so without a misfire. If I am unable to do that, I have a bunch of test loads to shoot this weekend. Either way, I’ll follow up when I am able.

Did the op say what stock he was using. Another thing to consider would be the rear action screw might be thru the stock and action enough to touch the striker. I am not familiar with this type of action to say for sure without having one in hand.

 

[gunsandgunsmithing]

What is the typical Firing pin protrusion ? .035 -.055 ?

Yes...around .050-.060. Like I said though and like you mentioned, say the extractor holds it but it still has some looseness there. It softens the blow enough to cause it. I've seen it a lot when fireforming say a dasher using the hard jam method. The fp hits the primer pretty good but if the bullet can move at all in the neck or lands, it cushions it enough to cause misfires on some. That's one reason I prefer the false shoulder method over hard jam in those instances.

 

[ShtrRdy]

For the last few posters -- the problem was solved. No need for further speculation.

 

[NorCalMikie]

How many .000 can a case move while held by an extractor ?

Just enough to get FTF!!! Who cares about the measurement. When it happens, you'll wish it didn't!! Don't believe it? Keep fighting it till you've had enough. Some folks have to learn the hard way.

 

[Sniperhandle]

Yes, I've seen new brass that was around .015 short. No big deal once it's properly fireformed but that's enough, especially with hard primers. I find that most fire but a few just won't.

It also depends on what type of extractor is being used, A claw extractor will usually hold the case better and you can get away with more excessive headspace, Because the claw extractor is also putting some sideways pressure against the chamber/boltface.

 

[AlNyhus]

When I f-formed the 30 WolfPup cases, it was with a Panda with a standard sliding plate extractor. The bullets were jammed a bit and the shoulder was blown forward .240 . With hundreds of cases done this way there was never a failure to fire. With my 30BR's, I intentionally push the shoulders back .020 via a shortened shell holder prior to the first firing. Again...never a failure to fire.

Ready to f-form on the left, fired case on the right:

 

[Florida Wally]

Did the op say what stock he was using. Another thing to consider would be the rear action screw might be thru the stock and action enough to touch the striker. I am not familiar with this type of action to say for sure without having one in hand.

It is a McMillan XIT. I don’t think the rear action screw protrudes through the action. However if the firing pin fix and cleaning the trigger do not resolve the issue, I’ll look there.

 

[CharlieNC]

I will be interested to hear what causes NO firing pin impact, yet is not clearly visible upon inspection so I can be on the lookout for symptoms in the future. Light strikes can be a pain to diagnose, but NO impact without clear cause has me stumped.

 

[AlNyhus]

It is a McMillan XIT. I don’t think the rear action screw protrudes through the action. However if the firing pin fix and cleaning the trigger do not resolve the issue, I’ll look there.

Unless it's been modified, the rear action screw hole on Pandas and Kodiaks are a blind hole. I do the through hole modification on them along with opening up the area over the trigger. -Al

 

[JEFFPPC]

What would bumping shoulders have to do with a FTF ?

Think about it. I bet you can figure it out. Not trying to be difficult but it's common sense. If your stuck ask, I will help.

 

[NorCalMikie]

I’m not stuck at all, I’ve already made it clear that I’m not on board with a few extra thou of headspace causing FTF.

Some folks won't believe anything so, move along, nothing to help here. And if you can't see the issue, at least we tried.
Hope you DID find your problem.

 

[JEFFPPC]

Be a hard head. Don't take advantage of problems others of had by trying what worked for them. Guys like you are reasons why guys like me quit trying to give advice learned from many years of shooting and personal,experience backed by 10s of thousands of rounds fired.