My gas gun load development

[Burt Gummer]

It seems I overlooked W748 when choosing a powder. I tried TAC, Varget and A2520 and settled on A2520, and coincidentally came up with 27.16gr pushing 108ELD-M avg 2471fps, sd 6.5 es 15 from a 20" BA premium 1-7 barrel.

Using my calibrated GRT model, a quick look at W748 appears to show that the two are near identical with W748 being just a bit faster and higher pressure. Where A2520 burns after passage at 97.8%, W748 burns 100% with burnout just before muzzle.

Valuable burn rate info right there. I didn’t realize the two powders were that close. Who would’ve thought such a small difference could be so significant in the same barrel.