The caliber is 6.8mm SPC II which most folks consider to be an AR-15 caliber. The little cartridge really flexes its muscle with a 22" barrel in the strong #3 falling block action! The forend wood was easy to find but the #1 butt stock was not. It was a semi-inlet that I ordered out of Canada then fitted & finished myself. The hardest part was getting the stain color to match on the two piece stock.
It's a long story on how I decided on the 6.8 cartridge. Just let me say that loading & shooting this rifle has been a learning experience which is still underway. I'm amazed at the cartridge's performance!