Walnut bolt build

Two ideas to do that one. 1st can be dodgy but both things have done years ago.
1: Put two thin nuts (cut one in half and face both peices) on the very end of the thread. Lock them together just about end of shaft (bolt end) and turn the shaft from the nuts to the handel.( check balance at low speed)
When that is done put in vise with soft Jaws and hand file the left threads off to die size. Then run die down end for bolt connecting thread.

2: You could also bore out A piece of metal or wood so the bolt handel knob is a snug fit and it's the same length as the knob. Then cut that in half length ways. The gap left from the saw width should allow it to act like clamp around in lathe chuck. You can file the edges more if space not enough.
Second way safer buy far and useful for more.
Think a hacksaw cut is 3mm.

Looks good, have you installed it now?

I've had a play around using some walnut off cuts to make a bolt handle for a crosman 2250 build.