Percussion revolvers chain fire prevention.

[Darto]

This guy has done thorough tests. (He also has an 8 part online book all about shooting black powder revolvers). Page 2 is chain fires.
His thesis is that chainfires come mostly from crushed powder trapped in the tight gaps between the sides of the ball and the chamber walls. And that using any grease is what attracts this crushed powder because of the resulting stickiness.

https://geojohn.org/BlackPowder/RevolverMobile.html

[Alan Block]

Happened to me with an ASM 3rd model Dragoon. I figured it was caps falling off the nipples from the shock of the first shot. Two adjacent cylinders went off. Shot the wedge out and I lost it.

[keepitlow]

Crisco over the cylinders.

[Flintlock Tom]

Crisco, lard, peanut butter, Bore Butter®, etc.

[G-forceJunkie]

I use those grease/wax covered wads between the powder and the ball, never had a chain fire and never grease over the ball.

[prob]

Originally Posted by G-forceJunkie

I use those grease/wax covered wads between the powder and the ball, never had a chain fire and never grease over the ball.

This is the way I do it as well. Shooting black powder revolvers is messy enough as it is without getting grease all over everything.