Hi Dave,
The gun of mine you showed was a sleeved Rem 700, started life as an SPS 270 Win, still have the 1.25 barrel, 4000 rounds and it still shoots 8" at 1000yd. In the form in the pic, we had it opened out to 300win Mag bolt face, set up to bottom eject. The barrel was a Hart double Kryo, I got from JR, in 11 twist. Stretched in a 2" alloy tube. Chambered in the 300 Redneck(300 Win Mag, blown shoulders, longer neck). It was shooting 209gr pills in front of 2217, with 210m primers, good for about 3050fps. The stock was made of 1" Alloy plate, the stainless pods at the back were filled with lead. It was about 60lb from memory. TZ has bought it to make a 6mm LG, for 600yd IBS.
Jeff