Playing with a stock gun gives you a big weight advantage as well as a smaller profile, what you need to do is practice your snap shooting ,practice and practice some more , most times you have one shot then you can't come out again because of the paint coming in. Learn to move fast and you need to listen to your gut, timeing is also important, you put a real close shot on some players and they will waste a hopper on your bunker hopeing for you to stick your head out, wait and listen when the paint stops or tapers off come over the top or out low and you can catch alot of players looking while they reload. As I said before you have a smaller profile so play the bottom corners ,shadows whatever gives you an edge, become very aware of how much your exposeing and whatever you do don't become predictable. Double up in a larger bunker with another player with a semi, let them blaze away and trade shots, peek around the other side and poach players wide open shooting
at your partner, or sit quiet until the semi gets taken out, listen,
players on the other side will usually call that bunker empty, then you can possibly get 1 or 2 people looking. I love playing stock on
speedball field, nothing I know is more satisfying than takeing out a player with a high end gun, its absolutely devastating to them. Have FUN.