09-09-2015, 10:44 PM
You'll be fine with 18". Your station pressure is probably going to average ~24.4" Hg. The 18" will push 123gr supersonic well past 1400yds at that altitude.
Using the Litz G7 BC for the 123gr SMK (.260), you'll still be supersonic at 1450yds starting with a 2500fps mv. Your difference in drop at 1000yds between an 18" and 24" will be .8 Mils. Wind deflection difference will be .1 Mils.
Buy lots of ammo, and go shoot that bad boy.
Using the Litz G7 BC for the 123gr SMK (.260), you'll still be supersonic at 1450yds starting with a 2500fps mv. Your difference in drop at 1000yds between an 18" and 24" will be .8 Mils. Wind deflection difference will be .1 Mils.
Buy lots of ammo, and go shoot that bad boy.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com