I have 11 carbines (#12 is on the way, this is a sick hobby lol), one in an M1A1icon stock and never gave it any thought, I cannot imagine there would be any difference if the same action was in either stock. Think the mechanics of the action dictate where the brass goes and the stock would only come into play if it interfered with that process which I cannot see it happening with an M1A1 stock vs a regular stock IMO.