8.25-9 depending on velocity, altitude and temperature according to the Berger calculator. Kirby Allen ran them in a 7 Allen mag with a 9 twist with no problem. I ran the numbers for my 7LRM and my 8.4 twist had a 1.61 SG at 2950fps, sea level and 39 degrees. My 7LRM reamer has double the freebore of the Gunwerks reamer but it's not near long enough for these. Anyone who purchases these will have to get a reamer made for them unless your already throated for them.
Darren