Most all of us around here (home) use a ball diameter .005" under bore size, ie: .495"- in dead soft lead - we call pure lead, but it is only about 99% pure - plumbers lead it is called.
.010" under bore size (.490") can work well if the patch thickness is 10 ounce denim or thicker if a Rice or Getz barrel with round bottom rifling. You should fill the rifling to the bottom of the grooves PLUS having .002" to .007" compression of the ball by the patch.
Thus, the patch should be .022" to .0250" thickness, compressed. 10 ounce denim I measure at .022" compressed. Some batches ran .0225", ie: 22 1/2 thousandths of an inch thick.
.500" bore + .016" + .016" (rounded rifling depth) = .532"
.495" ball + .022" + .022" (compressed patch thickness) = .539" - which gives .539" - .532" = .007" divided by 2 = .0035" compression in the bottom of the grooves. 3 1/2 thousandths compression.
Using a .490" ball in this case, will allow flame blow-by in the bottom of the grooves, but with lighter loads such as 80gr. or 90 2f, there should be minimal of no fouling buildup, as long as a wet patch is used. If using 3F. I suggest you stay below 75gr.
.490" ball + .022" + .022" patch = .534" - .532" = .002" which is only .001" compression per side in the bottom of the grooves. This load might give adequate accuracy - or not- with heavier hunting or long range loads, there may be gas cutting. It should still shoot fairly cleanly, without much buildup - maybe none, but a thicker patch yet would be more accurate.
Most of us use a ball that is only .005" under bore size, with that 10 ounce denim (.022" patch) in square rifling which is usually .010" to .012" deep, giving up to .010" compression in the bottom of each and every groove.
That combination is ..495" + .022 + .022 = .539"
Groove depth with .012" rifling is: .500 + .012" + .012" = .524"
Thus, .539" - .524" = .015" divided by two = .0075" compression in each and every groove.
Is it any wonder we get no fouling buildup? With a proper crown this is not a difficult load to put down the barrel with a short starter and 3/8" hickory rod - shoot all day without having to wipe and achieve excellent accuracy = right of the bat with little or no load development - shoot 85gr. 2F and you are there, for out to about 75yards, even 100, however a bit more 2f will shoot better at 100 yards and further.
These are the types of combinations my wife and daughter use as well as a friend's daughter and wife - so - no, they are not too tight to load and they use only a short starter and the rifle's hickory rod- no mallets or hammers.
