The Savage 12 benchrest can be a fine rifle, it has a lot of nice features, but it is not perfect. The rifle is a production rifle, and is just like any other Savage from the factory. There is misleading beliefs, that the target action, is a special action, or that Savage uses special or aftermarket barrels on the target line of guns. The fact is the target action is identical to any other action except for the sear, it is cut at a different angle. The action is no smoother, and the barrel is exactly the same as any other factory Savage barrel, it is not hand lapped, or receive any special treatment. Just like any other Savage, the barrels are drilled at super high speeds, so it will have some marks all the way down the tube. Just remember this thing is not a custom action, it is not a Bat or a Panda, it is a production made gun, and will have looses tolerances. It will also have the same problems as any other Savage, but with that all said the dang things will shoot Great right out of the box.
Things I disliked about the Savage model 12 Benchrest, to start the barrel is too long. For some reason Savage saw a need to place at 29 inch long barrel on the thing. Because of the barrel length, I found that the gun is unbalanced, and wants to lift our of the rear bag. (Some people would disagree with me.) I also found that the stock has a lot of torque to it, and I contribute this to the height of the barrel to the bottom of the stock.
Just like any Savage with the target accu-trigger I have never seen one that will go down to the advertised weight, or work at the lower settings, somewere just under 1lbs is where you will find it works best. As well as any other Savage, for some reason there is a tolerance problem with the bolt heads, which can cause ejection problems, and it is magnified by short cases like the 6BR. Sharp Shooters Supply has been working to make aftermarket parts to fix this problem, and so far has gotten them to work well. The ejection ports on the target actions are HUGH, and are made to accommodate cartridges as big as a 284. At the cost that they are at, I would say that it would be close enough for someone to build a custom gun on a Savage target action, and have a gun with a better barrel and stock for close to the same price, but if you getting a great deal it is hard to beat.
besides all of that, the gun is super fun to shoot, many use them to shoot in IBS/NBRSA 600 and 1000 yard matches, and the guns have proven to be competitive. Some clubs have factory class, and these things dominate in them. If you want more information check out www.savageshooters.com web site.
Last thing, on twist rate, IMO 1 in 8 is the only way to go, you can shoot bullets from 66 gr all the way up to 108, and even heavier. I just feel that a 1 in 12 twist 6BR is a waste, it limits bullets availble, and has nothing to gain over a 1 in 8.
On accuracy, the gun will shoot just like any Savage, with handloads tuned to the rifle, it should be able to shoot around a 1/2 MOA right out the box. The one I had would average 5 shoot 100 yard groups under 1/2 inch all day long, with a few groups that measured in the mid .3's. At 600 yards it should be able to shoot an average 4-5 inch groups or better.