03-22-2016, 05:07 PM
So I went back to look over my ballistic data for this 123gr AMAX load, and I actually have muzzle velocity data from a range trip last year when I chrono'd some other loads.
My mv with 31.2gr of CFE with a 123gr Hornady SST was only 2435fps from this Lilja barrel.
I need to chrono these 123gr AMAX, but the velocities will not be higher on average, in my experience.
That means that the BC on the 123gr AMAX has to be a lot higher than .468 G1. That just doesn't work out.
By looking at where my actual impacts were at 1000yds, I ended up with 12 Mils of elevation.
Since I recorded the barometric pressure and temperature, I know what my critical atmospheric variables were.
I'm going to use .490 for a G1 BC, at least out of this 8 twist 17.6" pipe. I also notice that my impacts at distance are always high when using .468 G1 BC.
When I use the advertised .510, they are low, so we're somewhere in between is my conclusion.
My mv with 31.2gr of CFE with a 123gr Hornady SST was only 2435fps from this Lilja barrel.
I need to chrono these 123gr AMAX, but the velocities will not be higher on average, in my experience.
That means that the BC on the 123gr AMAX has to be a lot higher than .468 G1. That just doesn't work out.
By looking at where my actual impacts were at 1000yds, I ended up with 12 Mils of elevation.
Since I recorded the barometric pressure and temperature, I know what my critical atmospheric variables were.
I'm going to use .490 for a G1 BC, at least out of this 8 twist 17.6" pipe. I also notice that my impacts at distance are always high when using .468 G1 BC.
When I use the advertised .510, they are low, so we're somewhere in between is my conclusion.
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