Do you have a friend who is a machinist? Even a hobby tinker with a metal hobby lathe. He should be able to drill a hole, thread it, knurl the outside and cut it off to length. If you want to make it easy have him make both ends and then he can pick his own thread sizes. He just needs to hit the OAL.
Parts for a 60 year old, long ago discontinued gun, are just about impossible to find as you are discovering. But there are a lot of skilled people out there who can still make just about anything. But like most things of value they are getting fewer every day. Common sense, mechanical ability and thinking outside the box are getting to be a vanishing set of skills. Machinist, old ones anyways, or tinker hobbyist who build model steam engines are use to figuring out how to make all kinds of small parts.
