I've seen a number of original Lefever double rifles. I helped purchase one for a friend ( who has since sold it) plus the late Dr. Samson had two or three in his pocession when he passed away. This was a few years ago, but I think they all were in the .40+ caliber range. I don't remember the exact calibers. I think the barrel lengths were around 26", one was 28" and all were muzzle heavy. I never had the opportunity to fire any of them, sure wish I could have.
I believe Lefever Arms in upstate NY made a few for customers. Their barrel man was good at this.
Chris
