I have a new POF upper that I shot Hornady’s 75 gr. 5.56 ammo in and had 5 rounds out of 20 that their primers popped out of the fired case, causing the rifle to jam. I had no problems with any other ammo used, including the HSM Tactical 5.56 75 gr. The chamber is marked 5.56, not .223.
Have you heard or seen this problem? Is it a bad lot of ammo or a out of spec chamber?
There have been some reported problems withe the Hornady 5.56 TAP blowing out primers. I would contact Hornady and give them the lot number and they will take care of you.
The HSM shot very well with less smell/smoke, no popped primers with the same accuracy. I did not have my chronograph nor did I shoot beyond 25 yards that day. Tomorrow I plan more extensive shooting. Also, with the suppressor it shot with no problems. My POF upper has the 9" barrel.