I have a smith and wesson m&p .40c that I have had for about 8-10 months brand new. I haven't had much time to shoot but I have put about 500 rounds through it. I understand it's a carry weapon (that's why I got it) and it's got a short muzzle so my accuracy isn't going to be great. The first 100 rounds I shot I was pretty accurate with tight groups at 7 yards. The next 150 rounds I seem to be shooting 5 o' clock from where I am aiming. I went shooting yesterday and from 7 yards out aiming at the center of the target I was hitting all over. Very inconsistent and quite frustrating. I don't think it is me (well I hope not) because I am pretty accurate with my Kimberly custom 1911.
With the cost of ammo I started yesterday to collect my shells for reloading purposes. Everyone of my casings has a dent in the same spot. I will include picture. But is this normal with my gun? I never noticed it before. Could this have something to do with my inconsistency?