So, every casing my AR ejects has a nasty dent in the side. I'm running a Bushmaster lower, a Stag upper, and it happens irrespective of ammo type. Does anyone have any ideas on how to avoid this? I'd like to reload my 5.56 casings.

How nasty is nasty?

Every semi-auto dings the case during the ejection/loading cycle, usually in an individual manner. You can take two cases from two weapons and tell which one fired which case by the dent patterns.

I just reload them and don't worry about it.

Funny this topic should come up today, as I just ran about 200 rounds of 1x fired .223 brass through my single stage press today. It takes a lot longer than a progressive obviously, but I get to handle the brass after it's deprimed, and decide which pieces I want to discard. I think I tossed 3 pc. Two had dents that IMHO were bad enough to cause me concern, and the third had a nasty looking (uneven) case mouth. I guess it's a personal decision at to how "bad" the dent/ding is, but a jam is a lot less of a concern if nobody is shooting back at you :-). -TomT

I just re-read your OP, and IF it's EVERY case, or almost every case, I would think there's something going on with your gas system and/or spring in your rear stock. I'd have to defer to the people on this forum that know more about the workings of a AR to determine what part is causing REALLY banged up brass. I can tell you I have 4 AR-15's (3 Colt's & 1 Stag), and none of them beat up fired brass too badly.
My friend has a IMI Galil .308, and that thing will take military or commercial brass, and bend it at ALMOST a right angle after firing. -TomT

Every AR does this. Solution is pretty simple. Either cover your brass deflector in a 1/4 inch or so of black RTV silicone and replace as needed or put the loop side of sticky back velcro over that deflector. Its doing its job, but in the process it dings the neck.

Has nothing to do with the gas amount etc.

One other thing that helps a hair, buy an extra ejector spring or two, then pull the ejector and trim the spring so the ejector and spring, not under compression, sticks up above the bolt face about 1/8 inch or so, then pin in under compression, ejection is not so violent and it starts tossing cases to 2 oclock a few feet in front of you generally in a nice pile, rather than 5 oclock and 15 feet away... the spare springs are in case you nip too much....

combat rifles are designed to fire and eject every last time.... they don't care about reloading the brass, hence the "overengineering" at times.

Thanks for the info, all. This is my patrol rifle, so I guess I'll stick with the reliable ejection over a softer extraction. I'll see if our armorer will let me try the silicone or velcro trick. I don't reload that much, but I have several friends who do and I was gonna hook them up. Ah well.

Dents are easy to take out if you are giving the brass away... I know I wouldn't complain at all.

If its patrol rifle, then don't cut the ejector spring.

BUT I've had both done to my competition rifles and I've NEVER had a failure or jam etc.... of course that was some maybe 15 years of shooting and around 8 of those were AR only, in that time frame we went through around 20K rounds of ammo a year in the ARS....

Velcro would be by far the easiest and least invasive. And ain't gonna impair the ejection or function of the gun at all.

BUT your armorer has to ahve the call adn I bet he negates it.