AR15 popped out some primers today

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oley55

New member
I had a few hundred 55gr FMJ bullets from Everglades Ammo kicking around that I wanted to load up for general plinking. I had previously loaded these over some H322, but have since been using H335 for my 55gr bullets with good accuracy. Knowing these cheapo bullets would never be very accurate, I decided to use the same accuracy load of (24.9gr H335) that I use with 55gr Hornady VMAX boat tails without doing a standard load workup. With 24.9gr being on the low side of my original min/max (24.7-25.9 gr), I did not anticipate encountering any high pressure signs.

So today at the range I was using these rounds as plinkers for initial shots before fine zeroing a new scope n rings. I fired a couple with no issues and then fired one and had the primer back out upon firing. Had three more primers back out in the next 7 rounds. Looking at those that did not back out, I did not see any signs of excessive pressure. A little flattened but nothing alarming. I went ahead and finished up zeroing using my VMAX loads without incident or pressure signs.

So now I'm scratching my head. Both the 55gr VMAX and 55gr FMJs were loaded the same day, in twice fired LC brass, and CCI #41 primers. Besides a very slight difference in bullet profile, the only difference is I crimped the FMJs and not the VMAXs.

I can only guess that having the LEE Factory crimp on the FMJs, changed the combustion and bullet travel down the barrel enough to get a secondary detonation or something........................???

Weapon: AR15, 5.56, 24" HBAR, 1:8 twist.
(FYI, I also had a 16" AR on hand and tried the 55gr FMJs in it and had 1 of 3 rounds back out a primer as well.)
 
Bullet profile could be a contributing difference. Crimp definitely contributed to some extra pressure. My guess is that it was a combination of them both. God Bless
 
When you say backed out , what specifically do you mean ?

1) Are they backing out just a tad ( a few thousandths and are still in the primer pocket ) ?

2) Did they back out to the point of falling out of the primer pocket ? or are now loose in the pocket and can just fall out ?

3) Now that you have the cases back home . Have you tried to seat a new primer in the case/s that the primers backed out of .

1= primers backing out just a little can be a sign of under pressure . There is not enough pressure to stretch the head of the case back against the bolt face leaving a small gap between the case head and bolt face . The primer then backs out to the point it hit the bolt face .

2= over pressure or loose primer pocket to start with

3= to check and see if the primer pocket is stretched out . If so , to much pressure .

Also , measure the diameter of the 2 different bullets . If the FMJ is thicker , that can cause pressure spikes . that along with a crimp and the possibility of the FMJ having a harder jacket then the V-max . You combine all three and you can raise pressure quite a bit .
 
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My first thought is loose primer pocket. How many times has the brass been loaded before?

Any chance we could get some pictures?
 
popped out as in primer cup free floating around inside the action. First discovered when bolt would not fully close and lock. Found a primer laying down in the locking groove.

as stated they were twice fired. i.e. original LC production, demiled by me and then reloaded and fired with either 69 or 77 grain Sierra Match Kings. So this would be the third loading.

My first thought was over swaged/loose primer pockets with Dillon swager, but then rejected that as a likely cause since I had already reloaded and fired these. Also, in the past I had over swaged and ruined a bunch of mil crimped 38spl cases and learned a lesson. I now swage the primer pocket just enough to allow seating a new primer with solid pressure. I will generally ruin one or two primers out of a hundred because of overly tight pockets. Not ideal, but better than having a fire control malfunction from a loose primer hanging up in the works. or "so me thinks".

Been busy doing grandpa (parenting) stuff and haven't had the chance to to begin a thorough examination of components. Just put the little "big" guy on the school bus and am now heading to the garage and reloading bench.
 
most certainly caused by over pressure. just pulled five bullets and weighed the powder and found 29.9gr versus the expected 24.9gr. I use an older Redding balance beam scale and I must have placed the large slider on 25 versus 20!

I have two thoughts:
1. thank goodness I didn't have a catastrophic failure.
2. I am so very, VERY disappointed with myself. How could I have been so careless and done such a bone headed thing? What a dipstick!!

Thinking I may have to invest in a digital scale or a new brain housing group, or both.
 
just pulled five bullets and weighed the powder and found 29.9gr versus the expected 24.9gr. I use an older Redding balance beam scale and I must have placed the large slider on 25 versus 20!
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Well glad nothing to bad happened there . I use a Redding beam scale as well . The one thing I do is use check weights to zero my scale before loading . You may want to do this as well . It would have caught that . I also leave the check weights out and separate in the weight I'm charging as a secondary reference in case I'm confused as to where I'm at . It helps in load development when loading up 10 different charges . I can confirm what the last load was I charged because I used the check weights before charging .
 
You have a 24" barrel using a ball powder.

If the only symptom is popped primes, and not enlarged primer pockets or bulged brass, then the odds are very likely on a secondary pressure spike hitting your chamber during the extraction cycle and pushing the primers out of the pocket when the bolt face isn't locked in position.

It happens with fresh milspec ammo too, from time to time, even in M16 and M4 length barrels.

Jimro
 
Jim , you must have missed his update . He over charged the cases by 5gr . That will cause pressure issues every time . :)
 
reference:
I use a Redding beam scale as well . The one thing I do is use check weights to zero my scale before loading . You may want to do this as well . It would have caught that . I also leave the check weights out and separate in the weight I'm charging as a secondary reference in case I'm confused as to where I'm at . It helps in load development when loading up 10 different charges . I can confirm what the last load was I charged because I used the check weights before charging .
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Not sure how you can use a set of check weights to match a specific charge. Even with multiple sets I don't see where I could check 24.9 grains against a set of check weights.
2 20 grains
1 10 grains
1 5 grains
2 2 grains
1 1 grain
1 .5 grains

Or more likely, I'm not correctly following you train of thought.
 
I made a .5gr weight and the scale has .1gr hash marks . So I can check the weight to with in a .5gr perfectly and when I want to check 24.7 . I use check weights of 24.5 and the scale set at 24.7 . when zeroed it should show - .2 low . Close enough for me . Same thing with 24.9 . I use a check weight of 25gr and set the scale at 24.9 . It is zeroed when it shows .1gr over 24.9 easy peasy Japanesey ;)

It helps in load development when loading up 10 different charges . I can confirm what the last load was I charged because I used the check weights before charging .
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When loading for rifle . I load in .5gr increments and is why I made the .5gr weight . I just stared loading for hand guns and It's a tad harder to check the weight when I'm moving up in .1gr increments . I do give it a try though the way I explained above . It seems to work I guess :) .
 
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most certainly caused by over pressure. just pulled five bullets and weighed the powder and found 29.9gr versus the expected 24.9gr. I use an older Redding balance beam scale and I must have placed the large slider on 25 versus 20!
Click to expand...

I never got 25 grains of powder in a 223 case. How the heck did you do it?

Glad you have all your fingers and toes. The AR15 is a very stiff design and protected the cartridge case well.
 
How could I have been so careless and done such a bone headed thing? What a dipstick!!
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Everybody makes mistakes. Now you've made yours. Don't forget it but you can move on now.

That's why all pencils have erasers.

P.S. Lots of times when I read about shooting mistakes or reloading mistakes (sometimes done by folk with loads more experience than me) I wonder about this hobby.

I don't really have any answers but I think stamp collecting would be boring.
 
<------ This knucklehead tried annealing a casing that somehow had a live primer installed.... after about a 10 second delay... BANG! Scared the living mr hanky out of me !!!
 
I second the motion that 29 grains of H-335 would be a nightmare to try and fit in to a .223 case.

Please double-double check what you thought you thought you checked! ;)
 
This is 29gr of H335 in a PMC case

GRR4ZN.jpg


It's pretty full but I think I could get a bullet in there no problem

EDIT:

In fact here is a 55gr bullet seated to 2.240 in a PMC case with 29.7gr of H335 , it can be done :eek:

5Cr0Vo.jpg
 
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Haha, :D, well, I can't fit max charges of Varget in 'em either so maybe it's atmospheric pressure around my bench!
 
I can get 25gr of IMR 4064 in a case and seat a 69gr SMK in it . That's how I knew I'd get the 29gr of H335 in there . I don't know what varget looks like but H335 is a very small spherical powder .
 
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