I have an NEF Huntsman that uses the PR 25 ACP conversion breech plug. I tested B209 in it using CCI small rifle primers. The day I tested it was sunny, over 80 degrees F and humid. I was getting slight hang fires. I am in no hurry to make B209 work in this rifle because T7 does just fine for my needs. When I get the itch to test again, I plan to test with CCI small rifle magnum primers to see if they work better.