I have fired over 6,000 nitro (smokeless) cartridges through my Joseph Lang completed March 6, 1866 and rebarreled in Damascus by James Woodward circa 1872. Obviously I have no hesitation shooting it with the 2 1/2 inch cartridges it is proofed for.

[Linked Image from live.staticflickr.com]2008-01-30 006 by Robert Holliday, on Flickr