Velocity and powder conundrum

[sundowner]

Sundowner, not to be jerk, but Hornady Ten says that max load using 123 SST and H335 is 26.4gr with velocity of 2300fps. Also Quickload shows that 28.7gr of H335 pushing a 123gr SST has velocity of 2553, with pressure of 58,585psi. Your velocity agrees well with the Quickload numbers. I am well aware that QL is only an estimation, but it seems that you have really hot load at 28.7gr. QL gives a velocity of 2365 fps sat the Hornady max load of 26.4,with pressure of 44,759psi using standard QL parameters for temp and elevation. I have used 25.5gr H335 and 123 SSTs with an 18 inch Grendel Hunter upper and have chrono'ed about 2250fps.

I use the powder manufactures load info and that load that you are talking about has changed over the years and additions , it has gone down , their load is below the fps listed on their ammo box .