YEP, THERE BE SUCH A THING, I'VE GOT ONE MADE BY EA BROWN & CO.. ACTUALLY IS A 7.62 X 39, BORE DIA IS .308, MATCH GRADE SHILEN BARREL, 15in LENGTH. IS REALLY ABOUT THE SAME AS THE 30 HERRITT. HAVE NOTED NO GREAT PROBLEMS, CASE NATURALLY HAS MORE TAPER THAN HERRITT WHICH I WOULD ASSUME MIGHT CREATE MORE BACK THRUST.(ACCORDING TO SOME EXPERIMENTS CONDUCTED BY PO AKLEY) BUT THAN AGAIN WHAT WOULD THAT OLD MAN KNOW. :-)