Howdy CCK,
That gap sounds tight. If it works, all the better. If it starts to drag, open it up some. I've found the Big Lube™ bullets to be very accurate. First off, they have very flat bases. Second, they have plenty big driving bands. And of course, Third, they carry so much lube that they don't loose their accuracy. The fact that they function well only adds iceing to the cake.
One thing I like about the BLB designs is that they feed well in my rifles. I run 'em thru Browning 92s, but they do slide thru very well. I'd sure like to hear how they work in some of the new trombone guns.
It's a lot more fun to shoot a match when you don't have to worry about your guns runnin' and hittn'.
DD-DLoS