Thread: .500" barrels

The barrel is rifled, so any drill will go bumping down it over the old rifling and probably stuff it up and a gun drill cuts only on one side . My take on it would be to make up an armours "D" bit, bore the breech end to just over bore size in a bit and make the bit to just fit in. Setup in lathe and with plenty of cutting oil slowly cut out all the rifling in one go. Then ream to required bore size and recut rifling. Speaking of recutting the rifling, I have just done that, so putting the money in here`s the 22" .510" bore Elephant gun barrel with six groves cut rifling at 1-24" twist .
, A .500" gun drill tip, cuts one side.
, 22"long , The new recut six grove rifling, bad pic.