bdhutier said:
1. I have two lbs of FFG triple seven. Will that be safe to run through this pistol? From what I understand, the pressures will be different from standard BP/Pyrodex, so I'll need to use less, right? (eg. 30gr/BP = 20gr/trip-7)
ffg 777 is safe to use in your revolver. However, three things to keep in mind: first, it does burn hotter and produce higher pressures, so reduce your load by 15% from what you would use with real black powder or Pyrodex. For example, if your real black load is 25 gr by volume, use .85x25=21 gr by volume of 777. And since it's ffg rather than fffg I'd round it down to 20 or even a bit less.
Second, 777 is sensitive to compression as has been mentioned. I'm not aware of any issue with it producing dangerous pressures due to compression, but it will produce inconsistent results due to incomplete burning if compressed, and may even fail to ignite at times. Raider's advice is worth heeding.
Third, it ignites at a higher temperature than real black, so standard caps may at times fail to set it off, especially with the compression issue. Some have reported better results with so-called 'magnum' caps. Some people duplex their loads, using a few grains of real black between the 777 and the cap to ensure ignition.
bdhutier said:
2. If anyone already owns one, what size caps fit best on stock nipples?
Frankly, cap size is a crap shoot. There is no standard definition of what a No. 10 cap or a No. 11 cap is, and even if there was there's no way a piece of stamped metal with a chemical paste inserted in it can be controlled to .001 inches and still cost 4 cents. So even within, say, No. 10 caps, there's significant variation. Add to that the variance in nipple geometries amongst manufacturers who are trying to guess what the latest cap sizes really are and you get chaos.
So, the best answer is to buy some and try them. You're likely to invest up to $20 buying different brands and sizes before you find one that fits. Until you need to buy another batch and find out they've changed...