Rem make 700 in two sizes , long and short , the long action will work with everything from 223 to 338 Lapua , it will need to be modified to do so but it can be done , the only thing "needed" to swap from a 270 to say a 7mmSTW or other magnum is a mag box for that case , if the rounds feed from the mag then they should eject fine
The 270 would need the bolt face opened up for magnum case head which is a simple task if your having the action blueprinted anyway , I'd personaly have a Sako extractor installed also.
The action is long enough but the feed rail may need some minor tweeking to feed the fat cases but generaly just a mag box up grade will work , at this point I haghly recomend that you have the Wyatt's mag box installed it will give you alot more room to seat the bullet out later down the road if needed.
All this work is gonna cost between$250 and $500 depending on the smith. Since you already have the action then I'd build on what you have but after throwing all that money at it you ware still stuck with a rem 700 that you will likely get none of your money back out of if its sold.
OR , you could buy a Borden or Stiller action and have a ready to go custom action that will retain most of its value and it'll save your smith a days work on your build.
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