Fortunately chain fires are very rare if you take much of any care at all.
I find that in a .44 that 30 gns of black powder gives a nice solid kick without being over the top. And if you load with no wad or filler like I do then 30gns of powder is pretty much the minimum you need to allow the ram to seat the ball on the powder. With black powder and the BP substitutes it's important that you do not allow the ball or bullet to sit over the powder with any sort of significant air gap. Pressures peak to much higher levels as the amount of air goes up. Proper loading sees the projectile compress the powder from just barely touching to a moderate pressure. Ideally you want to feel the ball land on the powder through the lever. I often feel a slight "crunching" feel back through the lever when the ball contacts the powder.
Some form of lube is important to aid in keeping the powder fouling soft. The common one is some sort of grease/wax mixture over top of the ball. Another is a lube filled wad that goes between the powder and the ball. Another more rarely seen option is the one I use. I put a drop or two of Canola cooking oil down on the joint between the ball and chamber wall. The oil wicks around the joint fully on it's own and viscosity holds most of it in place. It's far less messy than the over ball grease mix and far less costly than buying lubed wads.
If you have a brass framed gun then you want to limit the charge to more like 20 to 25gns of BP or subs. You'll then need 10 gns volume worth of a filler between the powder and ball to make up the distance. Cream of Wheat is one commonly used filler. Oat bran is another. Makes for a toasty smell along with the black powder sulphur smell....
Some guns do better with .457 round ball. If you find that the wire edge is thin and sometimes isn't a complete ring or doesn't occur at all you'll want to try some .457 size balls. The ring that gets shaved off should look like a ring of heavy carpet thread. If it looks like a ring of common clothing thread then I'm thinking that your chambers are telling you that they need the bigger size. Now some guns have been given a slight trumpet like mouth on the chambers. Such guns won't shave any lead at all. But they do swage a flat ring waist on the ball. It just does it by forming one instead of cutting away the lead. Such forming vs cutting chambers should still make you push on the loading ram lever with a good 8 to 10 lbs of pressure. If it's any less then the balls are too small.
Caps need to fit the nipples well but not be so small that they don't seat fully. I found that it's better to have caps which are too large and simply pinch the end into an oval shape before loading than to have caps which are too small and simply won't seat so the compound is against the rim of the nipple. No compression from the hammer pinching the compound between nipple and hammer face = no BANG!
My experience with the Itallian guns is that out of 7 only one would accept CCI #10's. The rest all have nipples that are too large for these. Instead I use CCI #11 or Remington #10's.
Yep you read that right. The companies do not have a consistent number to size from company to company. Just another part of the "mystique"...
One more item on powders and measuring. The use of volume "grains" is linked to black powder ONLY! Because BP is so consistent from maker to maker and fairly consistent from grade to grade it is possible to mark volume measures in "grains" which will drop that many grains WEIGHT for black powder. So if you buy and use proper black powder then a 30 grain volume measure should drop 30gns by weight of powder.
Note that Pyrodex and the other subs are NOT the same density as black powder. So when they say to use the same VOLUME they mean it. Do not measure out any BP substitute by weight or you'll seriously over charge your gun.
All the best with your new toy. Come on back if you have more questions.
Oh, one more thing. When I put the caps on the nipples I use a push stick made from a good softwood like Fir or Hemlock to seat the caps firmly. This has reduced the number of failures to ignite the caps by leaps and bounds and I highly recommend it. But at the same time I also strongly recommend that when you hold the gun to seat the caps with a push stick that you do NOT fold your fingers around the front of the cylinder. Smoothly applied pressure should not ignite the cap. But all the same you now have an officially loaded gun and you do not put your body parts in front of the openings like the mouths of the chambers which are capped. Besides, if by some chance seating the caps DID produce ignition you don't want your fingers around the front of the cylinder anyway.