I have an NEF sb2 45-70 which I reamed to 45-120 also, as I had that reamer on hand. It's the 22" barrel. I loaded .450 nitro equivelant loads in it for a few shots with a hornady 500gr., and it handles it, but the little gun is just simply not built for this. While fun for a few shots, it's not something I would consider anyone doing out of hand. It is simply dangerous in these. Mostly due to the design, and poor lock-up. Falling-blocks are the best.