Hey guys just built a new AR. Using Hardened arms 16" M4 1/7 Melonite Tactical 15" Quad Rail and Spikes Lower. Gun shot great the other day using .223 winchester bullets. Today I used 5.56 Independence rounds and every 5 or 6 rounds bullet gets jammed and I have to pull the charging handle really hard to release the bullet. It happened 5 times with just 2 mags. I attached a picture showing how there are the same markings on the case of the bullets each time it happens. Bullets are also bent slightly.

Do i just need to go back to .223?

Upper is suppose to be able to shoot 556 and 223 all day.



Any help would be appreciated.

Your feed ramps are new and sharp, guess they're catching on the unpolished 5.56 brass case neck and had an easier time with the .223 brass, which might have been fully polished.  It'll wear in.

So I should just keeping shooting hmmm. Just didn't want to mess anything up.

Yea looking at the 223 American Eagle rounds they are polished necks. Seems like this might be the issue.

Thanks!