Several years ago, when I was looking for an action to build a 20VT on, Zanders just happened to have a batch of Rem M700 SS actions with fluted SS bbls in 17FB, in CDL stocks, on clearance for what I thought was a very reasonable price. Bought two of them, kept the one with the prettiest stock. Pulled the bbl and sent it to Bartlein after calling them to order a 1-11tw .204 bbl to match the factory bbl's contour. It took several months to get the bbl blank, but by that time, I'd gotten a 20VT finish reamer & a set of Hornady 20VT dies, plus a 500ct box of R-P 221 FB brass (which turned out to be really poor quality, with about 12% of the cases having a primer pocket too shallow to allow flush seating primers). But when I got it finished, that little M700 action fed, extracted, and ejected perfectly.
I've re-barreled five of the Howa Mini actions, with custom bbls in 6.5 Grendel, 22 Grendel, 6 RAT, 20 Tactical, and 223 AI. All five have either DIP or Jefferson Outdoors aluminum DBM units, either EGW or Warne 20 MOA sloped scope rails, modified triggers set at from 1lb to 1-1/2lbs, and in stocks from Boyds, B&C, and McMillan. Jefferson Outdoors has a replacement bottom metal with a hinged floorplate that looks pretty slick, though I've not yet tried one. If Lapua was to start making 221FB brass again, I believe my next Howa Mini project would be a 20VT in a B&C Sporter stock with the aforementioned Jefferson BDL-style BM.