I've tried all kinds of primers with T7 powder. Did absolutely nothing for my groups or crud ring. I switched to Pyrodex P powder and got measurable benefits. More shots without swabbinb, no more crud ring. Supreme accuracy and consistency and costs 50% less than T7. It's the only powder I use in my inlines (T/C, White, Knight). You might want to give it a try if you haven't already, but check with your owners manual first.