UnaStamus wrote:Has the Federal ammunition been .223 American Eagle, or the XM193 5.56?
What was the other ammunition? (caliber and brand/model)
It's possible that you got a bad bit of Federal ammo that is underpowered, though it's unlikely. Federal is notorious for having higher than normal pressures, and XM855 and XM193 ammo both tend to be above established pressure limits. It's a rarity, but not impossible.
The possibility of a bad chamber is more likely than people realize. It's worth investigating.
Having said that, eliminate the ammunition first.
It was the XM193 5.56 i believe. I will have to check for sure as I do not have it with me right now. I think the other ammo was Winchester white box 5.56 and .223. I think the first thing I will do is get a box or tow of as many different brands as I can and run them through to see if it has any other trouble. Looks like I may do some more work to the gas block as well and see if it is causing any issues.