Quote from: Graybeard on November 30 2020 02:24:38 PM MST
I was getting an average of 1619fps with 155gr XTPs out of my AR carbine with a 16" barrel. The load was 10.0gr of 800X. The chronograph was about 10' from the muzzle.
According to the calculator at gun data.org, muzzle energy was 901ft/lbs. 50yd energy 672ft/lbs and 1397fps and 100yd energy 509ft/lbs @ 1216fps. They list the ballistic coefficient as 0.138 for that specific bullet. http://gundata.org/ballistic-calculator/
Hodgdon lists a max load at 9.8gr of 800X at a meager 30,000psi for 155gr bullets. Hornady lists a max load of 11.5gr of 800X for the 155gr XTP, with no pressure data.
So my thoughts are you probably can drive a 155gr XTP fast enough to get to 600ft/lbs at 100yds. But is that a good choice for the hunting applications that you mentioned? If a small deer happens to present itself at 50yds, or less, you are overdriving that bullet (XTP). Perhaps the better choice would be a solid copper, like the LeHigh. Or prove the muzzle energy with the 155s and hunt with 180s or heavier, if that's possible.
Thank you for your real world data!
I have been running bullets and velocities through the calculator and I'm getting the same results over and over again. You could probably find a legal load, but it's going to be pushing the cartridge to it's limit. A .357 lever or a .223 semi is probably the right way to do what I want to do.