I do not know the answer to the question. I would like to add that cmmg says not to use aluminum in their rifles and kits. I built an ar9 using a cmmg bcg and barrel kit. Went to the range with various ammo like I always do with a new gun. Forgot their warning about aluminum. The rounds came out crushed and the next round bent. Still clueless i tried to keep shooting aluminum and got the same results back to back. At that point it wouldn't even run brass. Failure to eject and load next round. Stripped down the bcg to clean it and that helped a little. I then noticed the bottom the bcg had some small gashes. I lightly sanded it smooth and has been running flawless since.
Aluminum is definitely softer then the metal the bcg is made of. So how it caused that damage and issues I'm not sure. cmmg knows more then me so no more aluminum.
Very odd and did not know that about CMMG. I have their Banshee in x39 and it runs steel case like a champ with MP mags.
I started the thread cuz I remember a few on here warned against using it in the Scorpion and I have a bunch of Al cased ammo, and started to wonder - then when I searched I can only find threads of people saying 'dont use Al cased..." with nothing to back it up.
So, I asked.
BTW - Blazer Al, has been flawless for thousands of rounds for me in my CZs and other guns. In fact, better than the Blazer brass for me.
In my Scorpion, I have used it in the past, and steel cased ammo with no problem.