Have you done a water capacity test to the top of the neck ?
I found 20N29 gave the best velocity over 50BMG & RL50 in the VM2 imp I built.
24N41 is a bit faster than 50BMG so might not be much help to you.
I have both & have built both.
I really like the Norma magnum, the only draw back I can see with the Norma mag is the lack of case taper.
My Barrett 98B that I re-barrelled into 338 NM appears to have little or no primary extraction, once the brass has been fired a few times it gets...
That isn't the colour of any ADI powder that I have ever seen.
ADI make the H4350, it is ADI 2209.
Also didn't someone post up weights that were different to the H4350 data on the packets ?
I modified it a little to fit the old 6 port T5 Terminator brake.
I found group size was unchanged but moved to the right 2-3 moa at 2050 yards, some of that may have been conditions ?
6 port T5 Terminator muzzle brake.
5 port T5 Terminator muzzle brake.
I ran the 110 Vmax with 20.5 Littlegun at 2.105-2.110" stunning accuracy in my DPMS 1-7 twist... as usual this was fine in my firearm with my brass.... YMMV
I just replaced my Barrett M107-A1 with a Steyr HS 50-M1 shot it on Thursday night with some low loaded ammo from the Barrett.
Looks like it will shoot.
I have the 720, 762, 798 & 802 CEs to try in the Steyr as well as the ADI FMJs.
The Barrett.
Nothing to do with the 140 Amax issue, but I bought a heap of Hornady 450 Bushmaster loaded ammo for the brass.
There was two different lots, same packaging, when I pulled them the powder weights between the lots there was a grain different ??
I'm not even sure it is the same powder.
Didn't...
The throat isn't important with the Cutting Edge projectiles as they are bore riders, the bearing surface is the same from 325 to 425.
Cutting Edge Bullets
I got some of the 450s when they first came out.
Unfortunately my Custom 416 Barrett doesn't like them.
The velocity was well down on the Monos, so it was a kinda lose lose situation, slower with less BC...... & not as accurate .....:-(