Re: 300 Win Mag
High Desert Hunter,
I just pulled my 300WM barrel off my Savage, and it was still shooting well at 1688rds. It was starting to head downhill, but I think it still has another 100-200rounds left in it for closer range shooting. Keep track of your throat erosion, and expect to see it move forward .003"-.004" for each hundred rounds you put through it. Adjust your loads to suit. This barrel grew about .003" for the first 400 rounds, but stabalized after that, and has grown much less. I don't have any experence with rugers, but Jimm's son has a stainless ruger 300WM that he used on Pdogs in the texas panhandle last fall, scoring on a few out at 600 or so yards (with a 3-9 scope no less). He may be able to offer additional information on throat erosion rates in your barrel.
Id probably expect 1300, more with conservative loading, cleaning, and allowing that barrel to cool when its time.
Just keep chasing the throat, and eventually, precision will start tapering off, and it time for another.