I have fired around 56,000 rounds of 45/70 loaded with 10 grains of Unique under a 385 grain cast in various TD's. Both original, H&R reproduction and rebarreled original actions. On the rebarreled action I have over 20,000 through it. Zero hint of a chamber ringing. A small percentage of those had heavier bullets and more Unique.
I do not use a wad. Wad related chamber ringing was an issue in the late 60's when I started and I have limited experience with fillers.
If Unique and chamber ringing is a problem I would think that I have seen some evidence of it in the 80 pounds or so I have put through TD's
Cleaning black powder is very easy and not as time sensitive as most would believe.
Pyrodex left or not cleaned properly has destroyed a very large number of firearms.
I got a deal on 5 pound of Blackhorn 209. Only used it in inlines.
http://www.blackhorn209.com/wp-conte...tridgedata.pdf
http://www.blackhorn209.com/faqs/