Primers pop out?

[cyclesurvival]

So I went up to shoot my AR. I had shot a couple of mags and noticed a jam. cleared it and continued to empty that mag. I started picking up my brass and notice a case with out a primer, then found several with indentations on the case base. The indentations matched the poped primer. found another poped case. I was shooting new brass cased federal 556 55grain ammo from bi-mart. Is this a normal thing that happens? I shot several more mags and only had it happen one more time. I did pull the bolt and check everything before doing more mags. no signs of over presure, deformed bulging cases.
Could this be a bad batch of ammo. I have been using it and have over 2000 round down the tube with no problems.
Thanks in advance for the help.

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[Bon Sauvage]

Were the primers flattened?

 

[cyclesurvival]

no the first one was smashed to s-it the second one looked normal no signs of high presure.

 

[Bon Sauvage]

A bad bunch of ammo is certainly not unheard of hence military primers are staked in place. Since you have had no problems with your other ammo I would tend to believe it's a bad batch. If you have the time for an Internet read it seems to be covered fairly extensively.

 

[madcratebuilder]

I was shooting new brass cased federal 556 55grain ammo from bi-mart.

Try some genuine nato surplus. I have heard of others having occasional primer problems with Federal 5.56.