50/70 questions

[Kurt]

With the .495/515" bore you will be slightly handicapped and you will get a mould that is .515" diameter plus maybe .516" for a GG bullet if that is your choosing. A PP bullet patched to bore .495" will have to be on the soft side so the obturation is sufficient filling the grooves or you will ge gas cuts and that will start what you called a walkabout. A hard undersized GG bullet will have the same results.
I had a mistake barrel on one of my rifles that had deep grooves that gave me fits and even spending countless hrs lapping the lands to shallow up the grooves using a cut brass lapping slug for just cutting down the land tops showed improvement but never satisfactory results with the bullets and alloy I wanted to use.

I guess this one case were you should do what the rifle wants and not what you want to use.

Merry Christmas All.

Kurt


By the way; Welcome to the forum.