well Yes, a 13% increase in shot load gives 1.27oz versus 1.125oz so actually just over 1oz & likewise as circumference is based on dia & not ia aquared you would get an increase of bor contact of only the 6.3%, so at max range the 10 will always have a "Very Slight" edge over a 12. The point is it is "NOT" astronomical & is probablly beneficial to about 1 shooter out of about every 100 thousand shooters who concentrate only on attaining the absolute maximun range from a shotgun.
Now I have absolutely no way of proving it & I realize you are going to tell me I don't know whereof I speak, but am going to go out on a limb anyway. I will thus say that for every thousand crows you have killed with a tan gauge you could have killed just as cleanly at least 975 of them with a well loaded 12ga.
I shoot shotguns because I enjoy it. Virtually every shotgun I ever shot was "Fun" to shoot & at some point I have shot from a 2' .410 to a 3 10ga, I enjoyed them all & each has a place. Being more than 60 years though since I shot my first shotgun, A H&R 28ga single, I will say, there is virtually nothing which can be done with a shotgun, which can't be done with a 12ga while staying within todays laws.
A 1000 crows is pretty close to my latest annual totals. I would say the use of short 10 has allowed me to increase the number of my kills by about 10%, perhaps a little more. One reason for that is I will take shots at birds that are not fully committed or exiting a setup at ranges where I would not take the shot with a standard 12. The 10 not only gives a little performance advantage ballistically it also gives one confidence to take the tall ones. The 12 is always going to be restricted over a 10 due to bore size, it may not be much by diameter and volume but the performance increase in the field is greater than those numbers might suggest. The 12 is always going to be the 10's little brother, saying it can do the same thing a larger bore does is simply wishful thinking or rationalizing one's choice to use a smaller bore. I hope the original poster buys that Lefever and finds out for himself.
