Marrakai and Mike,

I am in Marrakai's camp. I have used NfB for some 30+ years. The instances that I have heard about chamber ringing were when the reloaded cartridge used a card or wadding over the nitro powder. Charlie Dell did some experimenting with small charges of nitro causing ringing and I believe that is what he found; that is, that the powder was confined and when ignited, the pressure built up due to the confinement and then when the pressure wave reached the bullet, it caused ringing.

To prevent this from occurring, I believe Wright, Seyfried, and others recommended using open cell foam rods (similar to what Kynoch sells (or sold)) to hold the powder in place. That is what I use.

In using NfB, I believe it is very important to follow the guidelines of Wright and Seyfried in terms of powder and loads.

In years past, duplex charges were used. I have not done that. If one does use a duplex charge, they need to properly reduce the black powder for the energy generated by the nitro.

Now, all that being said, I have never heard of black powder causing ringing so that is the safest route.