Air Arms Owners Club

Looking into it with a torch should tell you, a generous squirt of degreaser will help to loosen the grip of old compacted grease etc.

finners wrote:Bosun,

You have checked that there are no 'spacing washers' at the base of the piston...? They are sometimes there, but are difficult to get out. Invert the piston and give a few sharp bangs of the latch rod end onto a piece of wood, so's not to damage the latch rod. It is very unusual for a standard spring to be producing 11.8 ft.lbs.

Finners.

Many thanks. I'll take a look there first. On previous AA springers, the pre-load washers have always been on the spring guide rod.

Mmmm....... No washers in the piston, so I think I'll give "collapsing a coil" a try. I watched the videos and it seems pretty straightforward. However, there was no mention of re-tempering. OK, the collapsed coils will be fine, but what about the adjacent live coils?

Dont worry about re tempering. Just heat up the end coil that you want to collapse. Collapse it and let it cool down in air. Job done.

Just to add, you probably know anyway but, do it at the front (muzzle) end of the spring, less stress there.

Sake-san wrote:Just to add, you probably know anyway but, do it at the front (muzzle) end of the spring, less stress there.

Thanks for that. No I didn't know. But why should there be less stress at one end than the other?

I know not the technicalities but, it was advice passed to me by two of the UK's pre-eminent tuners
Gary Martin understands engineering stuff, perhaps he will have an answer?

springs tend to fail at the rearmost coils. greater stress at this end. when trigger is released, the coils at the piston end open/destress first, then the coils behind start the process. the rear of the spring is forced toward rear guide, opposite/ reaction to the piston being forced forward. piston also trying to move forward whilst hitting compressed air, sending forces rearward, rear of spring gets a harder time due the the lag in coils opening whilst forces coming back up the spring when they are trying to destress/open.