[jjk308 In Memoriam RIP]

If your rifle wont shoot close to a 3 inch group at 100 yards it may need either rebedding or counterboring.

Bedding problems are usually caused by worn out bolt holes, worn recoil lug recesses or warped forestocks. You want the action held firmly by the stock with no side or down pressure from the forestock, only a little upward pressure on the front of the barrel is acceptable and free floating the barrel as in the Finn 28/30 is best.

Counterboring is needed to correct poor accuracy if the rifling is worn off near the muzzle due to cleaning. Usually if there's even a little squiggle visible from the rifling at the muzzle crown it'll be OK. Completely worn smooth it needs counterboring:

I've never had a problem counterboring, even with my little chinese tabletop drill press. Just use a 3/8" top quality 45 deg. (standard) bit (NOT A CHEAP OR WORN OUT ONE!) at the proper speed (600 rpm if i recall correctly), set the barreled action up vertical and parallel to the drill and so the bit will swing out right over the bore center. Make sure the drill is fairly tight, minimal wobble. Use plenty of cutting fluid or motor oil to keep it cool, make short cuts under enough pressure to cut the bore continuously. if you're too cautious and let it rub instead of cutting it'll just get hot. Pull the bit out and inspect for good rifling around the cut. When you hit decent rifling you're done. Knock any chips off with a piece of brass or plastic.
I've never had a problem centering either because the 45 deg. drill bit really wants to go right down the center of the bore or maybe because I'm so anal retentive I get it perfectly centered and straight. I've always gotten back within 3 moa - about 3 inches at 100 yards.

 

[jjk308 In Memoriam RIP]

I got a Weatherby Vanguard in 300 Wby Magnum for under $350 - BRAND NEW.
Of course factory ammo is $2 a round but I reload and it costs little more than .30-06 that way. 7mm mag Weatherbys were the same price at Walmart on clearance of old stock if you want cheaper shooting and a less sore shoulder.
The Vanguard (Howa) is a very standard mauser type without the 3rd lug - fully adjustable trigger, no corners cut, all forging and machining.
The 300 Weatherby Mag really reaches out and touches someone - none of that wimpy .308 bullet drop!
I put a Nikon Team Primos scope on it - ultra bright Golden Monarch optics, unobtrusive BDC, on Burris signature rings and mounts - easily does 1 MOA with no tuning of loads needed so far.
This rifle has made me swear off even thinking of more sporterizing of milsurps.