Sounds like a pretty complicated process with a lot of work to keep the impact medium consistent.

Since you have a chrono, why not consider a simpler project such as a velocity comparison of increasing powder charges (5 or 10 grain increments)with the same bullet.

If he starts at around 60 grains and shoots 5-shot groups at 60, 70, 80, 90, 100, 110 and 120 grains (or even 60, 65, 70, etc.) it should show significant increases in the average velocityat the lower end of the scale and deminishing returns as the upper end is approached.

Still a lot of shooting and data, but not so much mud.