kwhi43,
Fact? You have test data to proffer?
You realize of course this flies in the face of 175 years of experience don't you? Mykeal is wrong about what Samuel Colt did, I have 3 original Colt's and none of them are chamfered. I will post the pics if you like, I've had this discussion before.
Hellgate and I usually agree on matters concerning cap guns, but on this one I have to disagree. Black Toe Knives is correct, the best fit will always be a cut fit. That is unless there is a burr like ROAshooter first talked about.
My experience is not just from data about revolvers, I had to deal with a problem much like this with a high speed production tool dispensing lead balls and I wished I could have shaved a ring, it would have solved our positioning problems.
ROAshooter started this discussion about chamfering by telling us how he fixed an existing problem with a mouth, not adding chamfers for any other reason.
Swaging balls contrary to what would seem "intuitively obvious" does not necessarily give you an "interference fit." This is what we found with the equipment, there is actually a bit of spring back. In addition if there is any lubricant or chamber residue it creates a film between the chamber wall and the ball when swaging it. This is why lubricant is used during swaging, it creates a film. If you cut the ball the interface is clean and the oil film or debris is pushed in front of the peripheral contact patch as the ball is pushed in.
But a burr or rolled edge into the diameter of the chamber will cause you a problem. If there is one then it needs to be removed and avoid adding a chamfer if possible. A very small 45° or steeper chamfer that remains smaller or about at the ball diameter will still work most of the time. Steeper, not shallower, you don't want a gentle lead in. I have a question for those of you that "swage," if it doesn't shave lead how do you know if it has fully engaged the walls?
I suspect tapered chambers is your problem. This happens as the reamer gets worn. On cartridge guns it makes the throat in front of the bullet get tighter because the reamer is introduced from the rear, on a C&B cylinder it makes it smaller the deeper you go in from the cylinder face because the reamer is obviously introduced into a blind hole from the front. Get my drift? It fits "tightly" where it is but even a thousandths of forward movement makes it looser, you tell me where it will go.
The good news it can be reamed again. It might not even be larger at the mouth when you are finished, but you need to ream it to at least the seating depth with a constant straight sided wall . Find someone with a pin gage set to determine what the current diameter is for each chamber and how deep the pins will go. Then you can ream all of your chambers dead on to size, choose the largest diameter mouth, or .0005" (1/2 thousandths) larger.
Check these people out, they have tools at a good price and free shipping if it's ground. I just pulled up a Ø.451 reamer to show you.
http://www.atlascuttingtools.com/products/0.451-DIAMETER-%252d-A52262.html
Regards,
Mako