Building A Spring Compressor
A tool you'll need for working on your springers
Some Thoughts on Spring Compressor
Chip Gibbs

Several years ago (25) I got hold of an FWB124 sport from a friend. Right off the bat, I had to refinish the stock. It had been dropped on the street and I couldn't stand the scratches.  Of course when I took the stock off the action, I had to see just what was going on inside.  I didn't realize that the spring was almost as long as the whole air rifle.  It took me some serious figuring to get that spring back inside.
Some years latter, the internet was born and I was reacquainted with my old FWB, Jim Maccari and spring gun tuning.

Here is my version of a spring compressor……
As your can see from the photo, It is a simple device and I have seen some that are  even more simple, but, the less you put into it , the better the chance of a big spring trying to take your eye out.

This tool, built specifically for the FWB has a couple safety features not found on
Some I've seen. There is a hold down for the spring chamber and the barrel goes through the stop block. These two ideas keep the spring from arching up and out of the tool.  To do the compressing, I used a cut off C-clamp (not my original idea) bolted to a one inch pine board, although Oak looks a lot nicer. All the pieces can be Cut from the same board.  I just happened to have some scraps lying around.  I also made a sliding block to fit over the C-clamp's screw end to protect the end of the Air rifle action.  The stop block could be moved on the board to facilitate different sized actions.

There are no specific sizes to building this spring compressor, no plans or drawings for your specific model, just put some thought into it and do a little measuring and you should be able to put one together in short order.