I'm considering either a .36 or a .40. What are your average size groups out to 50 yards?
I've also owned one .40. It was one of Roundball's rifles I bought when he was reducing his herd. Using 70 grs 3F, a .390 ball with a .018 pillow tick patch w/mink oil (which was a very tight load in that rifle), it was the most accurate I have ever owned. It all but stacked PRBs at 50 yards, bench rested solidly in my Caldwell Lead Sled. If I was a target shooter, I'd still have that rifle. As a hunter, I didn't have a use for it. It fit the mininum legal deer caliber in MN, so squirrel hunting with it during open gun seasons when my deer tag was filled was out of the question as wardens would assume I am deer hunting. While I could have used it for deer, I like my .54s too much for that. Being red/green color blind, I need all the blood I can get on the ground.
My .36 Frontier (percussion) liked 25 grs of 3F T7, while my Kibler likes 35 grs 3F Swiss. Both a .350 ball with a pillow tick mink oil patch. Bench rested, both were/are sub 1" out to 50, so still 'minute of squirrel head' accuracy. Of course I only wish I could be that accurate in the field offhand or even resting on a tree or my knees sitting!
I don't think you can go wrong with either, but I also think both are more than needed for tree rats. I really debated with myself on the Kibler in .32 vs .36. As a dedicated squirrel or rabbit rifle, a .32 is hard to beat.
I will add that I've used my .62 smooth rifle with shot the most for small game over the years. Yeah...I'm picking out some shot while cleaning game, but that gun just delivers out to 25 yards...even to 30 on occasion...on squirrels and rabbits. Offhand...no issues. I've even taken some on the run on tree limbs. Plus, it's a great turkey gun in the spring! As I've said before...if I could only have one gun, it would be my smooth rifle.
