I finally got out the feeler gauges and on the Spillar and Burr that looked like it had been fired, between the frame and the barrel, the .004 fits with .005 too tight.
On the Old Army that was not fired, the .010 feeler gauge fits and .011 is too tight.
The replacement cylinder that I saw at Cabellas in Northern Indiana, was a little too tight to fit all the way into the frame.
I have read that for modern revolvers .006 to .007 is the target, so the Spillar is tight and the New Army is loose.
I assume when you fire the gun and things heat up, the brass frame should expand more than the steel cylinder and barrel so the gap would, perhaps, open up?
When I got an old Iver Johnson in .38 S&W with a huge barrel to cylinder gap, I pulled the barrel, machined one thread width of thickness off the face (so the front sight would index), then took off a couple thousandths off the barrel face until the cylinder fit, then worked a bit off the face until I got to .006 with the barrel torqued so that the front sight lined up.
I have not test fired it yet so don't know if there are forcing cone issues.