I believe you need it 3x3. It needs enough beef to be sturdy. We have found that the small blocks like on the light guns didn't work very good. I also prefer a glue in verses clamp block. No stress on a glue in. They use a set of Allen screws on each end to center the barrel and when the glue is dry, remove or loosen them. I believe Mark King rifles sells them. MattThinking about building a Heavy Gun with a 1.450" Barrel 32" to 34". Who makes a 9" long by 1 3/4" wide by 2.00" Tall Bbl Block.
What do they cost $$$.
I saw one that I believe Bill Shehane offered! But no longer has.
Thanks
Steve M.