I have a nice little 8.15x46r German stalking rifle, had it for 35-40 years, never shot it. Here is the problem. I slugged the bore, wide groves narrow lands. Measures .307 across the groves, but if I rotate the slug, I have to open the mic to .316. It would appear the groves are flat bottom. I have a Lyman 466 that cast .311 and 2 molds that cast .317, which should I use. I have 15 or so German schuetzen rifles, all chambered for 8.15x46r and have never come across this style of rifling. This rifle is a falling block proofed in 1906. Thanks for any help.
Mike
