I usually hunt cottontails with a longbow or a PCP air rifle, but when the temp's are below freezing I use a .22, they are too tasty to use anything bigger. Jackrabbits are a different story, they taste OK, but they are like chewing an old tire. Most states classify them as a non-game animal so I prefer to hunt them with a big bore. A friend of mine hunts them with a .458 Win.

Mark, I would love to see your drilling, it sounds like a perfect small game rifle.