I have seen broached rail blanks for bolt action reciver before recently. id love to build one there are lots of aftermarket 700 bolts out there now for around $100 even on ebay .
Tempering the reciver is the biggest issue id have. but with a few carbide cutters any thing could be done.
id love to see a broached an treaded blank to make a single shot no mag bolt action out of. there are lots of take off barrels out there cheap that could screw right on .
id love one for my 50 BMG .
If they can get $700 for a damm miled AK reciver im sure a lot of guys wuould pay $75 for a round tube with some slots milled into it an threaded on one end.