Long Time 300 WM Shooter:
I would consider how many rounds have been fired in this rifle. If it's less than 2,000 +- rounds and the lands and grooves look good(borescope). Your better off to have an Accuracy Tune Up done on the existing action. This would also involve shortening the barrel say 1/2 inch an cutting a new chamber in your existing barrel. Cutting a new recessed 11 degree crown, squaring the action (truing the threads), barrel, and the bolt face (this is also the time to install a Sako Extractor, new firing pin/spring). Lapping the bolt lugs, and raceways. Truing or replacing the recoil lug, etc.. Then glass-bedding your stock. You might as well install a Jewel Trigger also. The most critical step is having everything trued to the Center- line Axis of your rifle bore. This will cost in the neighborhood of $550.00+ versus $1,000.00+, to do the action with a new barrel. But, if you prefer a new barrel, than go with the best you can afford.
Everything I've read on this forum suggest you speak with Defensive Edge (Shawn Carlock). I spoke with him sometime ago. He's extremely knowledgeable and his cost are very reasonable. Don't trust your rifle to just any gunsmith. Pay to have it done right the first time.
I know of several police departments who have thousands of rounds fired through their sniper rifles that continue to have minute of angle accuracy. They all utilize the knowledge of a gunsmith with extensive aerospace machining experience that are held to .0001+ tolerance. DE demonstrates such expertise.
Where ever possible save your money to buy quality hunting accessories. Rack grade Remington 700 Long Actions/Short Actions are the basis for many working sniper and custom rifles.
***How through has your rifle cleaning been. Copper fouling has a significant affect on accuracy. If the patches are blue you need to clean. Also it is not uncommon for factory barrels to have tight sections along the bore. They can be removed with JB Bore Paste or non-embedding lapping compound #800. Clean the trigger assembly with lighter fluid and a drop of oil. Take the bolt apart and clean the firing pin/spring and oil. NO GREASE! I've have cleaned up allot of accuracy problems with my buddies rifles using this method.
GOOD LUCK
GONZO
SEMPER FIDELIS