I have a custom built 8mm Rem Mag. It is on a 700 LA Remington, and sports a 26"
Benchmark barrel. This cartridge is a hammer!! Shoots amazingly flat, and hits hard.
I drive 220 grain A-Frames to 3000+, and 200's to 3200. Recoil is brisk, and not for
everyone. A decent muzzle brake will tame it though. Reloder 26 is your friend, BTW.
Shot my elk last fall with mine. 220 A-Frame, 425 yards, elk never went 30 feet until
he was laying flat.
Brass is available if you keep your eyes open, or can be made from 375 H&H brass, or
300/340 Weatherby brass. Nosler also markets it, but a bit pricey. I love my "Big 8"
Dave.