A drill press and a very thin drill bit would be in order.But don't expect match accuracy out of them,as you are removing material to the weight of the powder charge. Doubt anyone makes a tool to do this, as most folks would just go and buy HP .22 rounds in the 1st place.

Maybe for a reason. Usually production is based on optimum size/weight/shape for a given charge.

If it's for dispatching mink in a trap where accuracy over distance isn't an issue you might try making dumdums by carefully cutting a cross in the nose of the bullet. You can also buy fragmented hollow points which have the same effect.

Lead solids, you could just use a knife!

Try filing the round nose semi-flat,like the old Remmy Yellow Jacket round. As it isn't for accuracy that should be enough to mushroom in the mink body.Or have a look about for Flobert BB round.It's just a single BB round ball sitting on a rimfire primer. With some guns its a PITH to load as a single shot,but they are quiet to the point of air-rifle.Originally developed for so-called "salon shooting" [indoor living room]in the 19th century.They might suit your work too?

There is also other hand/hammer operated units but hitting any live bullet in an enclosed steel sleeve is not up my street..

Regards Zx..

I think the PTB when after a man for seating his own bullets or pulling heads for one and reseating on a modified charge but as he didn’t have powder or primers as a separate component he walked..

CCI Quiets come in a hollow point too. Specifically a segmented HP that splits in impact. I’d say it’s exactly what your looking for.

I’m not sure who would have them. Might be worth ringing a few of the larger dealers. A poster mentioned he got them before, but a few years ago now.