That's not the important part. They were made for the PA season which was nothing but a PRB, so all were 1-66.

It's a shame TC didn't offer it in all the models. I think the majority of TC sidelocks are shot with a PRB. The 1-48 is ok for a PRB if the rifling is deep, but TC made shallow rifling more suited for conicals.

What they should have offered is separate barrels you could buy like the GPR. a conical barrel and a PRB barrel. They would have sold like crazy and there never would have been a need for the GM drop in barrels.