I've been doing this about 30 some years, had two chain fires. The second one I barely remember when it happen, but the first on sure suprised me.
Was the first year and me & a friend had bought new 1860 Armys. I had a traditions Pietta and e has an ASM. We traded Revs to shoot each others he loaded his I loaded mine. Both started firing and first shot baaboom! Sounded and felt funny, sorta just suried me bein'about a year into it. Was a chain fire don't know from what end. Nothin' harmed not hurt. Not a big deal if operating in a safe manner of dissapline.
Sawan article of a guy testing/simulating/assesing chainfire damage.
The Rev in a vice remotely discharged. Just frame and cylinder in a jig set off single and multiple discharges. The veloscity was extremely low enough to not cause death or dismemberment or damage a round to the side of a rev. Just be aware chain fires exist and practice safely...now go make smoke and have fun...