Use a hydraulic press or wood splitter, and extrude your own wire.
Someone posted a couple videos showing a Russian dude's set-up, that was quite an elegant solution. He used a large pot of melted lead to fill his cylinder, and his 'hole' was on a fixed plate on the deck of his press. The piston was pushed through, then allowed to stay where it was while the cylinder was refilled, and turned over, so as to push the piston back to the other end. That solves about the biggest problem I have seen guys worked up over, which is how to pull the piston out after pressing it in to the cylinder of lead.
The video...
https://www.youtube.com/watch?v=f_6CoRFtpuc&feature=emb_logo
I would suggest looking at Drill Bushings from the machine tool suppliers, as possible replaceable 'holes'. Once you choose a style, and make the cylinder, you can then change the bushing to make wire of the exact size you need.
Corbin sells a complete kit to make .22 bullets from rimfire brass, in it, they have a six cavity mold to cast cores. The idea is to cast them oversize, and get the uniformity by running them through the squirt die, which has the holes to allow excess lead to squirt out.
I looked pretty hard at Swaging, and figured that I was better off if I spent the money that would have gone in to swage dies and presses, on powder primers and bullets instead.
It looked like a good way to spend a winter afternoon in front of the bench, but it also looked like a way to spend an awful pile of money and time, that both were probably just as well spent elsewhere.
Oh yeah. Drill Bushings. They can be got in carbide, and in very precise diameters. A fella could do worse than to start there, if he was wanting to make his own dies. That's where I figure I would start.