My AR was jamming, what gives?

[Bartholomew Roberts]

I was wondering if I had a chamber problem and intend to try and polish it up a bit and was going to run some different ammo as well.

I've seen the problem you described with 5.56 ammo (like XM193) in a tight .223 chamber; but AE is .223 SAAMI already. Occasionally, you'll see the same problem with .223 chambers and .223 ammo when there are obvious tooling/machine marks in the chamber though. Is your chamber chrome-lined? If it is, then polishing may not be much help. If it isn't then, it may be worth a try though you would want to go really light with it and I'd still try new ammo first.