Whilst the wooden knob on the Loadmaster isn't too bad, I found that after a 100 or so rounds my hand started feeling a bit sore (not too bad, but I was aware of it). Unlike my other presses I couldn't replace the whole handle assembly without a lot of work so figured replacing the knob was the best bet. I made a collar to fit the end of the handle but as it has a slight taper it needed a bit of work in the lathe. Once I'd cut the taper (approx. 2.5 degrees), by fitting it and rotating back and forth I could find the high spots on the handle and file them down, resulting in a nice snug fit.
My original intention was to fit a "D" handle, as this would give a good grip and the force applied would be in line with the centreline of the handle. Unfortunately after making it and doing a trial run I found that the resultant extended handle was too long and at the bottom of the down stroke my arm wasn't long enough and I had to lean over the side of the chair! Not good!
So, I cut a piece of square stock and tapped it for 3/8" Whitworth, then found a bolt long enough to go through the new handle (foam handle bought at the rubber shop and a piece of broom handle turned down to fit and bored through), then welded it to the collar. Blue Loctite should hold the bolt in place, and I just need to shorten the clamping screws on the collar.
The handle tends to put the force applied a little off-centre, but hopefully it should work ok (certainly feels better than the knob).
Incidentally, I had to dismantle the handle assembly from the press and I found that one of the "axle" bolts had virtually no grease on one side, so I pre-greased it before assembly and then pumped grease into all the fittings!