Re: Savage parts for custom build
While ACE may have an argument, no doubt Remington 700 dominates the aftermarket parts category, I'd go with Savage. Jim Briggs at Northland Shooter Supply has Savage prefit barrels in many calibers. I've never asked about 300 Blackout, but its popular enough that I wouldn't be surprised if it were available. The Criterion barrels that he sells are phenomenal. Of course you know Criterion is owned and operated by Krieger. There are others like Shilen for a bit more, but I doubt you'd notice an accuracy difference. Headspacing a Savage is an extremely simple task...strip the bolt, close the bolt in the action, pop a headspace gauge in the barrel, screw it in until you get your desired headspace, and finally torque the barrel nut. I worried about accuracy, since a lot of custom smiths told me that the barrel nut was another "point to lose tolerance," however, when my barrel shoots raggedy one hole groups at 200 yards, I don't see how their services would have improved that at all. Only real issue is after market stocks. I obtained an LTV stock by watching the forums, but Choate has their tactical for budget minded buyers and if you don't mind the wait, McMillan or Manners produce stocks for Savage actions, so I don't see how its going to be much different from getting them to make a Rem700 stock...if you buy either one from them, you're going to wait 8 months to get it regardless. Bolt handles are easier to change on a Savage, again its easy DIY, with a common hex wrench and a replacement handle, you're set up with a tactical bolt knob and lever in seconds.
I'd choose Savage and not look back. YMMV.