for me, 9's are usually NPA, or poor trigger control
2 things to work on, passed on to me by one of the better offhand shooters ive ever met
RELAX. if you're not relaxed, you wont shoot a good offhand. concentrate, and start at your neck. relax the muscles, then shoulders, arms, core, and legs. you want to rely on bone support for any position, and if you're using muscles, you're gonna fatigue, and thats gonna cause bad shots
once thats done, relax your mind. you know what a good sight picture is (or at least you know what a 10 looks like). shoot the first 10 you see, and dont spend lots of time trying to pretty it up for X's. a 200-0x beats a 199-19x all day long. focus on that post, and let your position and NPA do the rest
second: ball and dummy. load 5 duds, so that they look JUST like your regular ammo. put 5 duds into your pocket, with your 20 round practice string (no point shooting sighters for practice). load without peeking. you'll catch yourself flinching, im sure....i know i still do. when you "fire" a dud, unload it, and put it back in the pocket. you want to be able to pull the trigger without your mind subconciously trying to compensate for recoil. once your 20 rounds are done, stop. 20-30 well aimed shots can be tiresome, and theres no point in practicing when youre tired/fatigued (again, perfect practice).
if i were you, id make sure i had a data book too. plot your calls (dont look through the scope). if you think you shot a 10 @ 6, mark it down. when you're all done, compare your calls to your actual hits (you wont know which is which, obviously, but you can see if things sorta match up). the added bonus to this? youve now shot a "blind" group. adjust your sights/zero based on the group, and not just the previous shot. if you've got a 6-8MOA hold, clicking 1/2 left and right isnt really helping you.
this WILL help shrink your group....but be aware, it takes TIME. ive been shooting for almost 4 years now, and i'm JUST starting to shoot some decent offhand scores (and i still have a long way to go IMHO)