Well ;
This is probably more for the larger scale builders than 1/350 or lower .Like maybe 1/72 or 1/96 . But it can be used in smaller scales if you are careful . Many manufactures mold the springs on the gun barrels and they are pitiful , Even the units from the so-called expert suppliers .
I have found on J.R.Haynes Forties I have to do this . I completely remove any molded on spring detail . You carefully use the X-Acto for the major part , then smooth and round the barrels with a coarse Flexi-File .
When that is done then you are ready for the wire . Take a four inch section of a bamboo skewer ( small ) Cut it off keeping the pointed end on the cut-off piece . Now sand it smooth as you possibly can . Get your wire from Hobby-Lobby or Hobby Town or many other craft places , or if you are lucky enough to still have a Radio - Shack in your town go there .
the wire size is very important . I use - for 1/96 and 1/72 scale - 28 gauge wire .with NO insulation on it. Then you get this home and do the following .Drill a hole in the flat end of the skewer piece . I use a #76 Rogers Drill Bit . Drill all the way through and sand the outer surface around the hole smooth .
Now .Take your wire and making sure it isn't kinked , put the bitter end in the hole . Make one loop around to lock it and start a very tight winding for the length of the skewer . When you start to feel the taper coming up, stop . Cut the wire at the skewer surface and put the end in the slot on the take-off spool .
Take what's on the skewer and twist it once with a medium squeeze .Then take the Xuron cutters and cut the wire where you put it in the hole , separating the spring you've just created from it's lock !
Now carefully slip this very tightly wound spring off of the skewer .Take a # 1 handle with a # 11 blade ( sharp or dull ) and do this , Put the blade at the very beginning loop and slowly roll it toward the other end .This will open the coils the amount you need .
Take the gun and measure the length you will need .Put the knife in the coil at that spot and cut through the wire there , Do that one more time .Now slip these coils over the barrels , being careful to hide the ends on the bottom as well as you can !
When they are in place , put a dot of C.A. at the base of the coils closest to the sight bracket base . What's this ? real re-coil springs on the gun ? You Bet ! Good luck with yours . Tanker - Builder