WMSRL #41 failure to ignite

[thumper3181]

I was working up some loads with these and out of less than fifty I had 5 failure to ignite, from two different gun. One Ruger American in 300blk and an AR-15 pistol in 300blk. On the ones that did fire I had decent SDs, so I'd assume that when they do ignite it's a consistent ignition.

 

[RegionRat]

@thumper3181 if at all possible, it would be great if you could do a careful study of those rounds that failed.

A photo of the primer dents that shows the primer depth.

Pocket depth being way too deep in some cases combines with very bad luck and short cases to fail ignition.

A shoulder datum check of the cartridge to make sure the shoulder wasn't set back too far such that the firing pin wasn't likely to set it off for example.

A careful disassembly of the round to check the condition of the powder and inside of the case for incomplete or partial ignition. Sometimes you can find contamination.

A careful gentle removal of the primer to be able to examine and photograph the inside end.

Weigh about 30 from the batch. See if the "bad" one sticks way above or below the batch.

If you go that far and don't find anything that looks wrong, it would be good to save a few of the other failed ones in case you decide to ask the manufacturer to examine them.

Be sure to wear your eyes and ears when pushing out live primers.

That is a high failure rate and is worth figuring out. It does suck to loose confidence in the loads so I wish you luck in debugging the failures.

 

[thumper3181]

I didn't have time to take any measurements, but I disassembled one and powder looked great. The primer just didn't go off, I put on a face shield and smacked it with a hammer and it did go off. Maybe they just have an extremely hard cup.

 

[Walt Krafft]

What cases are you using? Converted 223 cases? I would suspect the case shoulder dim is too short.

 

[bozo699]

I didn't have time to take any measurements, but I disassembled one and powder looked great. The primer just didn't go off, I put on a face shield and smacked it with a hammer and it did go off. Maybe they just have an extremely hard cup.

Thumper,
The 41’s are the same as 450’s but the anvils are different there built for ar’s so they don’t slam fire . I don’t know much about ar’s or the blackout cartridge but I’m guessing it’s a subsonic load and that’s probably your problem with them not going off
Wayne

 

[searcher]

When the shoulders are pushed back too far - the firing pin merely pushes the cartridge just a bit as it slams into it - if it even makes good contact to start with. Because you have this occurring in two different rifles - I'm guessing that is the problem. There are times when there are bad lots of primers - but they are truly rare compared to shoulders pushed a tad too far when sizing.

 

[thumper3181]

What cases are you using? Converted 223 cases? I would suspect the case shoulder dim is too short.

Two happened in Converted 221 fireball cases and the other three were Starline 300blk cases.

 

[thumper3181]

Thumper,
The 41’s are the same as 450’s but the anvils are different there built for ar’s so they don’t slam fire . I don’t know much about ar’s or the blackout cartridge but I’m guessing it’s a subsonic load and that’s probably your problem with them not going off
Wayne

I have ran CCI #41 and 450s without issue, two of the failures were supersonic. I also ran 50 CCI BR4 in the same cases but with a different bullet without a failure today.

 

[thumper3181]

When the shoulders are pushed back too far - the firing pin merely pushes the cartridge just a bit as it slams into it - if it even makes good contact to start with. Because you have this occurring in two different rifles - I'm guessing that is the problem. There are times when there are bad lots of primers - but they are truly rare compared to shoulders pushed a tad too far when sizing.

That's what I would chalk it up to, but I ran 50 ofthe same cases with CCI BR4s today in both rifles without failure.

 

[bozo699]

That's what I would chalk it up to, but I ran 50 ofthe same cases with CCI BR4s today in both rifles without failure.

I never thought about headspace at the time but that for sure will do it I think searcher and Walt are correct. The br4’s are easier to set off than 41’s
Wayne

 

[bozo699]

Thumper
I’ve also read about setting the 41’s for a crush fit to set the anvils a little deeper but without finding the article I’m not suggesting it just what I read
Wayne

 

[RegionRat]

I didn't have time to take any measurements, but I disassembled one and powder looked great. The primer just didn't go off, I put on a face shield and smacked it with a hammer and it did go off. Maybe they just have an extremely hard cup.

That they went off when smacked tends to point at something other than just the primer.

This particular primer is made to a Mil-Spec that includes safety margin testing in a specified test rig. However, that doesn't mean it is extraordinary in terms of ignition requirements, only that it is safe in terms of slam fire for use in semi and full auto. If an AR doesn't set it off, there is something else wrong.

Did you check the shoulder datum on the failed rounds? Any chance they were on the short end?

Was the primer pocket depth typical?

What hammer spring are you running?

 

[dellet]

Absolutely check the headspace dimensions and shoulder settings. Make sure that when you measure your fired case, that it was a high pressure load.

A lot of factory brass and converted that was made with the die set to touch the shell plate + 1/2 turn will undersized to start with.

Depending on the powder used, many of the popular sub sonic have such low pressure, that it will take 8-10 firings to actually reach maximum length. If you keep pushing the shoulder back, it never gets there.

A couple of the dedicated Blackout powders like CFE BLK are so pressure challenged that even as max load they barely create 40,000 psi and that’s just not enough to blow the shoulder forward in a single firing if the base to datum measurement was at minimum or less.

The early RARR’s were notorious for light primer strikes and failure to fire. The problem ended up being a combination of a bit of a generous chamber, and more often than not, under sized brass.

The primer cups on the Winchester primer may be a bit harder than the CCI. If that’s the case it brings another variable into play. Case design. There just isn’t enough shoulder. If the AR is over gassed, and most Blackouts are with pistol length tubes, you might be setting the shoulder back when it chambers. Measure a few and check to see if it’s happening. Save those that don’t fire and check base to datum. It also might be easier to crush the shoulder than the primer on soft brass.

Being over gassed for supers and suppressed, is a fact of life for any load that will cycle sub-sonic without the suppressor, or any powder that can do that.

If you use the 350 insert on the Hornady gauge, it should measure 1.070” minimum, 1.076 would be better. If you don’t have one, a sized 9mm case works pretty well, datum diameter is .3512”. Check the case diameter, it will be a bit large, but is close enough to check set back and firing growth.

 

[searcher]

That's what I would chalk it up to, but I ran 50 ofthe same cases with CCI BR4s today in both rifles without failure.

It is easy to dismiss primers as being bad when another primer fires in the same- sized cases. A lot of guys have experienced this (myself included) when loading Russian primers. They are fantastic primers - but will not fire all the time unless the case is fully "supported" in the chamber whereas the case can't slide forward much (like more than .005" or so). When other primers WILL fire - it is usually telling one that there is a headspace issue. I'd measure all of the 50 cases you fired (from base to shoulder) with a Hornady or other such measuring tool. I don't recall offhand what the firing pin protrusion is from a typical bolt - but it is not as much as some people push their shoulder back - and that is when these misfires come and go. I'd take the LONGEST case measured as being the one I'd use my setback to be based upon - and I'd not set the shoulders back more than .002". If, after firing it again, the length grows longer than your old longest measurement - this will be pretty much proof that your cases were pushed back a bit far. Using lighter loads, it is not uncommon for this procedure to take a few firings. Now - if you took your longest cases that you just fired successfully and didn't push the shoulders back at all - loaded them up and they then failed to fire with your suspect primers - THEN I'd say you have concern over the primers. Another thing you can do is take your measuring tool to the gun shop and measure a new, unfired round. If the measurement from your cases compares as being at least .003" shorter than the factory ammo - that will also indicate a headspace problem. The shorter yours are in comparison - the more the likelihood that is the problem. If you have a factory round at home - all the better for convenience.

 

[thumper3181]

I've always had great luck with about every primer that I've ever had, I think that I might have had maybe two that didn't go off before this. CCIs #41 are my favorite Blackout primers, that's why I jumped at the chance to buy the Winchesters version of them. The cases that didn't fire are 13 to 15 thousands shorter at the shoulder datum. I played with those cases today and fired just the primers in an empty case, every single primer that I tried works reliably in those including CCI #41, but I had trouble consistently getting the Winchesters #41s to fire in those cases. I think that it's just a case of bad luck with a slightly shorter cases and extremely hard primers and someone already said that here.

 

[thumper3181]

It is easy to dismiss primers as being bad when another primer fires in the same- sized cases. A lot of guys have experienced this (myself included) when loading Russian primers. They are fantastic primers - but will not fire all the time unless the case is fully "supported" in the chamber whereas the case can't slide forward much (like more than .005" or so). When other primers WILL fire - it is usually telling one that there is a headspace issue. I'd measure all of the 50 cases you fired (from base to shoulder) with a Hornady or other such measuring tool. I don't recall offhand what the firing pin protrusion is from a typical bolt - but it is not as much as some people push their shoulder back - and that is when these misfires come and go. I'd take the LONGEST case measured as being the one I'd use my setback to be based upon - and I'd not set the shoulders back more than .002". If, after firing it again, the length grows longer than your old longest measurement - this will be pretty much proof that your cases were pushed back a bit far. Using lighter loads, it is not uncommon for this procedure to take a few firings. Now - if you took your longest cases that you just fired successfully and didn't push the shoulders back at all - loaded them up and they then failed to fire with your suspect primers - THEN I'd say you have concern over the primers. Another thing you can do is take your measuring tool to the gun shop and measure a new, unfired round. If the measurement from your cases compares as being at least .003" shorter than the factory ammo - that will also indicate a headspace problem. The shorter yours are in comparison - the more the likelihood that is the problem. If you have a factory round at home - all the better for convenience.

I was originally mistaken, that it was two different head stamps, it was strictly new Starline brass. The case mouths and case length looked good so I just loaded. I should have checked, but it would be like finding a needle in a hay stack.

 

[searcher]

I recall the days before we had the cool measuring tools we have now - and just did trial and error using the old "turn the die down 1/4 turn" as came with the dies. Talk about "approximations"!

 

[thumper3181]

I recall the days before we had the cool measuring tools we have now - and just did trial and error using the old "turn the die down 1/4 turn" as came with the dies. Talk about "approximations"!

Yes, I know. But I didn't resize these cases, they came that way from Starline.

 

[RegionRat]

Yes, I know. But I didn't resize these cases, they came that way from Starline.

When you live long enough, you experience more failures...

I often catch flak on the forum for suggesting beginners include measurements of their virgin brass.... now you know why.

When we first started playing with AR platforms to be able to utilize Comm Block ammo (7.62x39, 5.45x39, etc.) we found some of the hammer springs being used without issues on our ammo would have statistical failures on the Comm Block stuff. Thus, the enhanced firing pins and upgraded springs were borne.

When you play around with AR platforms, it is good to keep things like alternate known value spring sets for the hammer and enhanced firing pins just in case you actually run into some Comm Block primers with the hard cups.

You may want to give an enhanced firing pin and spring set a try after you screen that brass and sort out the short shoulders, it may help salvage the brass and it takes all of about 5 minutes to swap out those parts and then put them back again once you have the first cycle done.

 

[thumper3181]

When you live long enough, you experience more failures...

I often catch flak on the forum for suggesting beginners include measurements of their virgin brass.... now you know why.

When we first started playing with AR platforms to be able to utilize Comm Block ammo (7.62x39, 5.45x39, etc.) we found some of the hammer springs being used without issues on our ammo would have statistical failures on the Comm Block stuff. Thus, the enhanced firing pins and upgraded springs were borne.

When you play around with AR platforms, it is good to keep things like alternate known value spring sets for the hammer and enhanced firing pins just in case you actually run into some Comm Block primers with the hard cups.

You may want to give an enhanced firing pin and spring set a try after you screen that brass and sort out the short shoulders, it may help salvage the brass and it takes all of about 5 minutes to swap out those parts and then put them back again once you have the first cycle done.

That's a good idea, I had to do that to my 7.62x39 upper in order to get it to run tula ammo.