Black around case necks on my gun, but not on others?

[cranebird]

What type hammer do we need for this method? I am getting ready to do some shopping...

I picked one up at a yard sale for $3.The barrel nut community reloading hammer, who do I send it to first ?


Do you realize how stupid I feel from thinking that unscrewing the nylon brush every pass through the barrel was helping ? That is time wasted that I'll never get back.....