You can make a leather seal without too much difficulty. Way easier with a lathe, quite possible with just a drill press or a hand drill, and could be done with some minor labour, without either.
The cheapest way would be to grab a chunk of the thickest, hardest leather you can find, and get some tubing of the correct diameters to cut a workable ID and OD.
You don't want to match the diameters so much, as you want to have the leather fill the seal cavity with just a wee bit sticking out once it is pushed in as well as you can with a punch.
I used a lathe and turned some on a mandrel, you could do as well on a drill press or with a hand drill and a Dremel tool or a bench grinder to remove the material.
Most of the job is in fitting all that leather into the seal cavity. I used a 1/8 inch punch and ran around the seal in laps, tapping it down a bit at a time.
Have you tried D & L Airguns? If they do not have a generic seal that will work, they may have a synthetic material one that can be adapted.
Cheers
Trev
