Most good conical shooters have a shallow rifling depth... on average that is what you will find. Slip-fit works in Whites with concicals because they will obturate into the rifling when the load is ignited thus going from "loose" to "tight"...

I see that T7 is still up to the same ol' stuff... that statement left me puzzled the first time I read it as well, and the second, third, fourth, ans even the sixth. I guess he is saying the secret of tight bores is accuracy... once you cut out all the other baloney. Could have been worded better... I am sure it makes sense to him though