Using a Rem 700 receiver..... there appear to be some aftermarket receiver's you can use . I'm in the early stages of gathering parts. You can glue the receiver in the tube or use a special round recoil lug. Do searches on the 6mm website,they're very popular in some shooting disciplines. I'm going to use the MAK kit because it allows the use of AR15 stocks. Hope this gets you started in the right direction,there is info out there its just scattered around.
Kevin McDonald lives in Seymour IN, which is only 20 minutes from house he makes the MAK and it is very nice. He is also very helpful with just about any question you might have. I have a 260 caliber and i love it. it is a real shooter. last Sept i shot it out to 1400 yards. hitting a 20" X 40" target. you use a rem. 700 action . Long or short. i used the short. the repeater uses a Accuracy International mag. and then you buy a barrel of your choice. i used 28"Brux with the interrupted fluting topped off with a shawn Carlock muzzle brake so i can see my bullet hits and the butt stock can be anything that will fit on an AR platform. He has a new feature that allows you to remove the butt stock with just one click of a button. so if you want a 30" barrel you can store it in a smaller case in just one click to remove the butt stock.