I have used both .355 and .356 in my STI 38 super with little or no difference in accuracy and velocity. I can also say the same for small rifle primers and pistol primer, hardly any difference, if any at all.
It was a great match. Stage 2 was really tough. I got 26 A's, 2 C's, and 7 proc. for forgetting to change a mag. I have been unable to find the results on USPSA.org. It is unusal to have great and breezy weather like we had. Who is going to GA.?