Howdy-
I'm going to assume that it's not operator error that's causing the problem. If you've tried several factory loads, or several well-made reload recipes, and all you're getting is patterns rather than groups, then the problem is somewhere in the rifle or sighting system. If you're using a scope, are you using a new one, or is it an old, reliable scope that you know and trust? Are all of the scope ring screws and base screws tight? Check the muzzle of the rifle for any obvious signs of damage or dings to the rifling. Shine a bore light through the barrel and check the bore to be sure that everything looks right. As long as you've got it unloaded, with the bolt pulled out for this inspection, you might as well clean the barrel down to bare steel with a good solvent, brass jag, and one piece cleaning rod, being sure to use a cleaning rod guide as well. Take the barrelled action out of the stock and inspect the inletting for any obvious high points that could be placing stress on the barrel, and check for sloppy inletting that may be allowing the action to shift in the stock during firing. When you replace the action in the stock, make sure that all of the screws are nice and snugly tightened down with the correct size screwdriver.
If it still won't shoot worth a hoot with a reliable scope, clean bore, no obvious signs of trouble or damage, and tight screws, you can try glass bedding the action, and making sure that the barrel no longer contacts the stock, or perhaps trying some light pressure right at the tip of the forearm. Without seeing your bench set-up, ammo, or rifle, that's the best advice I can think of. A decent gun should throw decent groups with pretty much any ammo that meets SAAMI specs. Some loads might be tack drivers, but most loads should print groups less than 3 inches, and the majority of groups with decent rifles will fall within 2 inches at 100 yards from a solid rest with proper shooting technique. Many rifles are capable of doing much better than that, even with a wide variety of loads. Start by fixing the gun so that it can throw groups of 2" or less on a consistent basis, then fine tune the loads that you shoot and see if you can break that 1" mark.
