They've also got the top of the nipple with a smaller surface area so lighter hammer blows will still fire the cap, a redisigned flash channel to focus the flame and moderately smaller flash holes (not quite as small as the Treso nipples). The few original Colts I have examined had nipples with fairly thin edges at the top of the nipple. I suspect in order to capture as much flash to channel it down into the powder. I also notoced that the originals had pretty large flash holes either by design or they could have been shot out.
An alternative to the new nipples is to just fill in the safety notch in the hammer face. It grabs caps and pulls them off the nipple afeter firing and then they get tipped off by the frame and fall off the hammer into the "works". Filling in the notch with JB weld eliminates the notch for the cap to lodge in. Thoroughly clean (wire brush, degreaser) the notch, make a masking tape dam, tip the gun up in a stand or padded vise and fill with JB. Set overnight, carefully file away the excess (Dremel with a brass wire brush works well) leaving a very slight dimple in the surface of the filling so the fill doesn't take a direct hit on the nipple. It occasionally falls out but is a cinch to replace. Brazing or welding would work the best to permanently fill it in.
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)