For starters, you've got some powders listed here that aren't really suitable for this particular combination. The Varget is about right, but if you want to reserve it for the 308 Win, that's fine. Still, it is an option.
Most of the other IMR and Hodgdon powders you've listed here are going to be too slow for this combination, particularly with the lighter (150 grain) bullets. IMR 3031 would probably be a decent choice for the 150s, but I haven't found data for this with the .311" bullets. Sierra lists this powder with a starting charge of 38.9 grains, and goes to a max of 44.4 grains, for about 2,700 fps. This data, however, was done with .308" bullets. It'd be useable for a starting point, but I'd suggest being cautious about working up to the maximum. COTW, 11th Edition also lists 3031 with the 150, with a maximum of 49.0 grains, but doesn't specify which bullet diameter was used for that data. Just watch your pressure signs and work in small increments. AAs 2520 should be about the right burning speed for this combo, but I don't have any data for this one. I'll keep poking around and see what else I can find. You didn't mention Vihtavuori powders, but I do have plenty of data for these, with a complete range of bullet weights.
Mr. Thomas and RT thanks for the help. I have not slugged the barrel, I thought I had some 32 cal Muzzleloader balls but I can't find them. Taking off the muzzle brake and measuring with a micrometer ( not the right proceedure ) but it's all I could do at the time. The bore appears to be between .3105-.311. The Wolf bullets it used to shoot with are .311. A funny thing happened when I was pulling bullets and reweighing the powder, there were 2-different bullets in one box ( 19 of one kind and one of another ) WOW WHAT QUALITY CONTROL. I have some Lapua brass coming try, at least that way I can eliminate the cases and I'll have real primers. I robbed some Varget from the stash and loaded the Sierra 150 gr Game Kings I loaded 47, 47.5, 48, 48.5, 49.5, and 50.5 and shot 7-shot groups for each and bore-snaked between groups. The 48.5 load was the only thing that even tried to group. I have tried another scope on the BP-02 Low Profile mount, and nothing changed, so I put the Mil-Dot back on it. I am going to try the original POSP scope and mount to eliminate the mount as a problem. It shot sub-moa with that combo out of a lead sled at our local 100 yard indoor range. I have shot alot of open sights so I'll probably even try that. Then the only thing left to try is to screw off muzzle brake and shoot to see if it's off centered. If you can think of anything else to try, please let me know. If I get rid of this rig I am going to take a blood bath on it with all the extra stuff and cases of ammo. Oh, I'm saving the Varget because it is so hard to get and I'm in the Texas Mid-Range Rifle Championships April 10th & 11th and I have enough Varget left for that and practice.
No, you should be fine there. My concern would be using a .311" bullet in a .308" bore with data that was worked up the other way around, that sort of thing. Just start at the minimum, workd slowly and watch your pressure signs. You'll do just fine.
I did not thank Mr. Thomas enough and all the folks that helped me with that post. I got real busy working out of town and ordered some Privi Partisen 150 gr FMJ and some 150 gr soft points to try in the interum. The point of impact was different between the 2 loads but they both shot sub MOA out of a lead sled with the front support pulled back to the front of the receiver since the barrel is not free floating. The 5-shot FMJ shot 5/8" and the soft points shot 13/16". Since the rifle is hard on brass, when I can find some more of this I'll stock up enough to get by. Here is a pic of a Long Range Pig Hunt. When I sent the pic to my brother, I told him "If you get far enough away, you don't have to worry about camo."
Here's a few pics of the rifle. Fitted a Dragonov stock, fitted EGW Space Comp muzzle brake, Tapco trigger, Kalinka BT02 low profile (centered) mount, we had to add machined pins and Red Loctite everything when we put the mount back together, the two way recoil with the brake was shaking the mount with the heavy glass. The Russian POSP scopes weigh a few ounces, the 6.5-20x44 Illuminated Milldot weighs over a pound and a half. The enercia on the mounting was taking a toll. We Tig Welded the factory side scope rail to the receiver and used Burris Extreme Tactical rings that were fully lapped top and bottom. And after all that, it came together and really started shooting. If I build another one, I'll do it all at once and be done with it. It is kinda nasty looking and people at the range usually can't keep away from it. It drops pigs like a brick.