I have another parameter to play around with to optimize your powders efficiency. After my testing today, just like Vettpilot mentioned, high density pucks give poorer velocity than loose pucks by a significant amount. The first 2 shots were with the same powder and mesh size than the third shot, but the density of the last shot was a lot lower. The first 2 shots were with grains that measured close to 32 grains measured weight to 30 gr volume, the last shot was with 24 gr/30 vol. notice the difference.
I can quickly linearize the puck making pressure to 30/32 * 24000 lbs to obtain 22500 lbs but I doubt its linear...so ill go for about 20000 lbs and work up as required to obtain an even 1.7 gr/cc
Of course you can say that it will balance out if you just use a volumetric powder measure, but you are using more powder to obtain the same result. Which means its wasteful and likely more fouling.
This is a big bit of news I think but terrible for me because I just finished making the whole batch into pucks.