Muley Hunter
I will just give my opinion on using JB on a new rifle. I use just a little the first time, just enough to clean out any nasty package lube. Then finish up with Hoppes and wipe it dry for inspection.
I usually like to try a few sabots for fit and then go shoot it. Since its a T/C you might need to give it a really good cleaning and a few extra passes of JBs. They can run on the tight side and they have some heavy packing lube sometimes.
JBs is really more of a good polish and cleaner than a true lapping compound. It will put a hell of a nice shine on it though and help reduce fouling/loading resistance.