I have a factory 300 WSM as well (Sako Finnlight) and I ould say the two biggest challenges would be ballistics and reliable accuracy. A good Vanguard can shoot sub MOA, but I believe they are ony guaranteed to 1 1/2 MOA. The Sub MOA Vanguard has a B&C pillar bedded stock. That's the first thing I would get a good pillar bedded stock and bed the action. Then maybe do some load work in it and see how it shoots. If you're not getting 1/2 MOA out to 400-500 yds, the LR accuracy may be questionable. My next step would be a blue print job. If accuracy is still lacking, next comes a custom match grade barrel in at least 26" and a heavier than sporting contour. (starting to look like a Sendero now) The added length is for velocity.
Then you need a bullet and load that will get you to 1000 and expand which may be challanging in a 300 WSM. I am shooting 180 E-Tips (which have a decent BC) at about 3160 or so with RL17 which is a very good velocity for that weight bullet out of a 300 WSM. Crunching the numbers shows me it will only get to about 880 yds, @ 3000' elevation, with 1800+ fps which is the minimum expanding velocity for that and most other bullets. The 208 AMax and GS HV 177 are two bullets with lower expanding velocities. That will get you to 1000. I personally wouldn't use the AMx at closer ranges. The GS has almost the same BC and will launch at a much higher velocity. I would guess in the neighbor hood of 3300 fps out of my rilfe with RL17. With that velocity, it's effect range goes out to over 1300 yds with an expanding velocity of 1600 fps. They are monometal, so I have no problem shooting at closer ranges.
Hope that helps,
Mark
