I have some AR comp on the way. Looking to try it with 88s. Lever is getting me the velocity but not shooting as tight as I would like. Still need to play with seating depth. Right now loaded as long as a polymer MDT will allow. Right around 2.55". 26.0gr of lever got me 2900 out of a 26", 33F degrees, 4910 altitude. I was seeing 3000 FPS with 26 grains of lever in 80 degree weather so it is temp sensitive. AR comp is supposed to be one of the most stable powders around and apparently Federal is using it in the 175 GMM, switching from 4064 (per the Alliant guy on accurateshooter)
"AR-Comp Offers Uniform Velocities over a Wide Temp Range
Tests were done with .223 Rem and .308 Win ammo, loaded with AR-Comp and maintained at temps from -20° F to +160° F in a controlled test center. The ammo itself was heated or cooled to targeted temps before testing. Across that range of temperature, -20° F to +160° F, the ammo loaded with AR-Comp showed a variation of only 20 fps in muzzle velocity. The primary bullet type tested was a 77gr .224 bullet and the secondary was a 175gr .308 bullet.
Burn Rate Like Varget: Though this is a reformulation of Reloder 15, the burn rate of AR-Comp is slightly faster than RL15. Alliant told us: “Reloder 15 is slightly slower, in burn rate, than Varget. The new AR-Comp, with the enhancements, ended up slightly faster than Reloder 15, so it is now very close to Varget in burn rate”. This is the result of the “tuning” of the powder to be much less temp-sensitive.
Meters Like Reloder 15: AR-Comp is a small-kernel, double-base extruded powder like Reloder 15, so it will continue to meter just like Reloder 15. The load density should be the same as Reloder 15.
Loaded Ammo: We asked if any manufacturer will be using AR-Comp in loaded ammo. Dick told us that: “he’s not allowed to release that information at this time.” Draw your own conclusions, but remember that Alliant is owned by ATK, which makes Federal rifle ammo."