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Alstone · Moderator & Site Supporter

When I striped down my TX to do a re-lube I noticed a slight nick in the piston seal also the gun was down on power by about 50 fps, so I ordered a new seal and made a tool to help fit it. The seal sits on a cone on the end of the piston and when fitting needs streching over the cone which is difficult, this tool makes it easy. I made it out of Nylon 66 but a hard wood, plastic or aluminium will do, it consists of a cone and tube with a hole big enough to accept the nylon cone, you place the nylon cone on top of the piston, place the new seal with the back facing the piston on the cone, put the tube against the seal and push the seal should slide over the cone which streches it big enough th slide over the stee cone on the end of the piston, a drop of silicon oil on the plastic cone helps.

Prise off the old seal with a screwdriver

This is the tool

Next line the bit up like this, Piston Nylon cone, seal, and tube.

Then push. Easy Peasy.

This works for most guns using this type of seal.

Al

WNCAGC · Member

if you soak the seal in hot water it makes it pliable so you can get it over the piston.

Even a hair dryer works the same.

Alstone · Moderator & Site Supporter

These seals are quite hard and heating with an hair dryer dosn't seem to work, Some makers actualy supply a cone to help fitting.
You are probably using Jim Maccari seals, or AA OEM seals

Al

AirGunEric · Site Admin

I use the heat method as well (usually laying a seal next to my woodstove for awhile does the trick) and then wiggle it on bit by bit with a very small, but strong, screwdriver to pull the edges over the piston cone. Once you've done it a few times it gets really easy- but the first time it seems to be a real challenge.