"IF" one does want to figure the % of the choke dia of the bore dia then choke/bore is not the proper way. As diameters are proportionate to the square of their diameters then it should be choke/bore or (choke/bore).
Thus a .693" choke is not 95% of a .729" bore but rather only 90%. Thus while it takes .036" to reduce the .729" bore by 10% with a 20ga a .615" bore it would only take .032" constriction to give the same 10% reduction.
While totally agreeing the actual pattern is the final answer knowing the constriction is certainly a good thing to know prior to purchasing a gun.
A gun with this amount of "Full" choke constriction s no more apt to give a desirable pattern for skeet o woodcock than is an IC choke apt to give a desirable pattern or handicap trap or pass shooting waterfowl. It's far better to buy what you want to begin with than start modifying all these old irreplaceable guns.
