I would add this to what has been said- Make sure the gun has no shine on it. Some will agree and some won't, but there are some stick on camo tapes that leave no residue.
Also a good pattern at 40 yds in a must....And I am not taking 5-10 BB's in the kill zone I want more. I have shot a Beneli Nova and I currently shoot a 535 Thunmbhole. The Nova had a Hastings choke that work well for me and got 30+ BB's in the kill zone. The 535 gets closer to 50 at 40yds. I use a SSX and I really like it.