Finally got a chance to put some rounds through the XM16E1 I got a few weeks ago. Put a bit over 800 rounds through the rifle Saturday, mix of LC M193, LC M855, Winchester 62 grain training ammo, and 55gr reloads. Even put a few 55gr True Velocity ploymer cased rounds through it to see how it worked. Wish I could say it ran flawlessly, but it had more than its fair share of malfunctions. Mostly magazine related, but quite a few weapon related ones initially. Those seemed to work themselves out over time, but the most concerning issue that remains is just how tight the chamber seems to be. Spent brass looks like I've rubbed it with sandpaper.



Top row some PMC brass fired from my in-law's AR, bottom row a mix of LC, Win, and FC brass fired through the H&R. Photo taken with flash to show case the scratches.

Possibly related, I had a instance of head-case separation on a FC case. The next round fed right into the case, and is now permanently attached to it. Ended up knocking the case out with a cleaning rod I brought in case H&R outdid themselves and made a perfect replica of the XM16E1s, right down to their problems. Well done guys! (I joke, this is more than likely a fault in the brass, I had similar issues with FC cases splitting almost a decade ago, and this one likely dates back that far.)

Anyone else ever have similar issues with the chambers being rough?