Our agency (a rural and not so rural S.O.) is currently using Speer 55 GD .223. It was selected last go round due to our then having a mix of 1/7, 1/9, 1/12 (1033 program) barreled rifles in use. The 1033 program guns are no longer in use. We currently have a mix of: - Colt 6933's (these are about half of our current rifles, this number continues to grow as we continue to purchase more over time; I envision us using only 11.5" SBRs 5 yrs from now. -Colt, S&W, BCM, etc. 14.5" and 16" mostly 1/7 barrels, but also some 1/9 barrels. I've reviewed info from FBI and other sources, and probably would have picked 64 GD (it seems to be the "just right" cartridge), but am curious about the 75 GD (there isn't much gel test data avail for it apart from Speer's website, which is from a test barrel), particularly: -terminal performance of the 75 GD out of 11.5" barrels using FBI method gel tests. What about rotational velocity? -stabilization/accuracy of the 75 GD out of the 1/9 barrels -any other differences, good or bad, that the 75 has from the 64, or the 55 GD, relative to our intended application Appreciate your help on this so we can make an informed decision.