Re: 30-06 long range Model 70 target
I've owned a couple and shot more of Winchester's Model 70 target rifles. They are pretty good out of the box, but have one common issue. The groove diameters in them are a bit on the big size. Both the pre-'64 broach cut and post-'64 hammer forged ones. With groove diameters of .3082" to .3085", best accuracy has been with bullets at least .3086" diameter or bigger. None of them shot heavy Sierra Match King bullets at .3082" all that well. With .3092" diameter Lapua's they did great.
If you can find some good bullets at least .3085" diameter, you'll get best accuracy. Sierra's 155-gr. Palma bullets used to be .3084" but I don't know what they are these days. If bullet making companies will tell you exactly the diameters their heavy bullets are made to, that'll help. Otherwise, you'll have to take a good micrometer to the retailer and get permission to measure some.
All Model 70 .30-06 factory target barrels had a 1:10 twist. Perfect for 190 grain bullets through 220 grain bullets at the speed max loads shoot them at. A match winning and record setting load back in its day with custom match barrels was 56 grains of IMR4350 under a Sierra 200 grain Match King bullet.