Have you considered adding small pocket 308 Win. brass loaded with a ball powder to the test?
I'd be curious as to those results well. I believe I have some shot strings stored in my silver mountain system of 7 1/2s vs 450s in .308 lapua sp brass with N150 and a 155.5 bullet. The 7 1/2s were slightly faster if I remember correctly. I'll be able to check in a couple of days.
I checked the data I had stored in my e target and find that for 10 shot strings at 1000 yards the 7 1/2s averaged 1292 fps, SD 8.6 fps and the 450s 1290 fps, SD 12.2 fps. Statistically a tie and I would need longer strings to validate any SD comparisons. My go to loads use the 450s.
I did lookup my notes on German Salazar's testing, and with a strain gauge equipped 6XC the 7 1/2s were about 1000psi hotter than CCI BR4s. He did not test the 450s.
