Spring stuff ...

I posted the following onto an airgun enthusiast forum in response to a question asking for tips when changing a mainspring ..


"The main tip is be very careful.

Second tip is make sure the gun is unloaded and uncocked.

For a spring compressor I use an old sash cramp - the long type that cabinet makers use to hold stuff together. I've made a couple of wooden blocks that fit in to protect the cylinder as well as an insert that goes into the back end of the cylinder and pushes on the washer behind the spring, and which then allows the retaining pin to be taken out once the spring tension is taken up by tightening the sash cramp. Generally I take the barrel off as it makes the cylinder more stable in the sash cramp, and to be honest I wouldn’t attempt taking the spring out with the barrel still on using my set up as I reckon it’d be a recipe for broken fingers.

I've just read that back and it sounds more complicated than it is.

Expect it to be messy as the old lube on the spring will be horrible, black, peppered with swarf, and as sticky as baby crap. Use lots of rag to protect your hands from crap and sharp edges, and remember how it all came apart.

While it's apart you might as well change all the seals and the buffer washer, and give everything inside a clean-up and a re-lube. T C Chambers are good for parts.

Third tip is take all the trigger parts out before you try to take the piston out of the cylinder.

Fourth tip is either draw a diagram of how the trigger goes together or take a photo. There are only 3 parts to the trigger and 2 pins so it's not complicated, but unless you like doing the rubic cube I'd suggest keeping a visual record of how it fits together.

Tip four and a half is give the new O ring a good soak in silicon oil (Abbey is good) for about a day before you put it on. Seems to help with gas seal and I'm told it lengthens the life of the part.

Tip 5 is be gentle when re-inserting the piston/head assembly with the new O ring into the cylinder as the metal edges it needs to be manoeuvred past can be sharp and they’ll take a slice off your nice new O ring.

Tip 6 is be sparing with the lube you put on the new spring. Don't get any lube down the tube in front of the piston ... silicon oil won't cause dieseling, but it will cause the rifle to shoot below power for a while. Use only an original spec spring (did I mention that T C Chambers are good for parts?) and be careful when you reassemble. There's nothing quite like being hit in the mush by a metal spring covered in grease.

Any help? As I say, I'm no expert and I'm sure other forum members can add some better insights than me. :) "