For BP loads, I'd look hard at the big lube offerings.
I have one for my 44's and one I use for various 38's (38 SW, .38 Spl, etc).
Also recommend holding off until you get a chance to look at the new rifle's bore, clean it very well & then "slug" it.
Good one on your new purchase!!
Lightning's are fun & have shot my Pa's 38 WCF with great delight. Very accurate & reliable when you know how to work it. His has a beautiful relined 26" barrel & shoots like a dream, too. Unfortunately he's not into BP anymore.....unless his iron runs low on ammo or has a malfunction & he's stuck shootin' mine ..hehe. Oh...I see he's working on a 44 WCF Lightning now, so I hope it has a good bore & he needs loan of my ammo.
humorous "Dig" intended to my friends at Colt Defense for "WCF" nomenclature rather than Colt's preference for 44-40, 38-40, etc.
Slim