Agreeing with much of the above ...
My Ruger #1V does not group well at all with either Nosler 55 or 50 Ballistic Tip bullets. It shoots very much better with the Sierra 53, and I think the old, old ones worked better than the current ones, but that could be within the noise in the data. It does best with either 52 grain Starke Red Prairies, but you can't get them any more, or with Walt Berger's 52 grain varmint bullet, bare. I've done well with H-380, but have not done an exhasutive test on powders.