I use bore butter in the bores of my muzzle loaders and have since they came out with the stuff so far back I can't remember. I also use it in the bores of my center fore rifles and shot guns.
It works just fine as a breach plug lube too.

Mostly I find how it was applied more than any thing the bore butter was a fault of.
If'n it works for you then keep useing it. If'n it don't then stay away from the stuff.

Al