A friend of mine, Doc Faraday, did that to his ROA nipples years ago. It allowed him to lighten the hammer fall for faster shooting. I dimple the nipples that have a fairly large surface area. If they have thin rims they are already "gathering" the cap flame pretty well. Good photo and a good idea to share.
With over 15 perCUSSIN' revolvers, I've been called the Imelda Marcos of cap & ball.
SASS#3302 (Life), SASS Regulator, NRA (Life), DGB#129
Wolverton Mtn. Peacekeepers (WA), former Orygun Cowboy (Ranger, Posse from Hell)