I forget what the bore measured out to but i think it was 30mm. My brother and i built this many many years ago and some time later a neighbor gave us a non working log splitter and we stripped it and started building off its frame. Dont make fun of the gold rims, You gotta have some bling bling right dawg?lmao.
Its a real fun shooter and will send a glow stick a good 200 yards. Valve springs and lifters also shoot nicely. Loads with 325 grains pyrodex RS, patched wooden plug and whatever else u want to add above the plug, we also have a jack that allows us to adjust for longer range now...............