Shooting offhand is really not for the inexperienced, casual hunter as you seem to be if you haven't shot the rifle since last season. I would suggest you buy a light weight pair of shooting sticks to shoot off of or even better is to buy the kind that attach to the front sling swivel and all you have to do is pop them loose so they extend into place so you have a decent rest to shoot from. If you do that, you'll need to shoot the rifle a few times with either one to see that you can put your shots where you want them. Either, in combination with using your sling, should help you shoot more accurately.