I removed the torsion spring on one and fitted a compression spring and guide
just had a look and it was on one of my pgp pistols but same frame as my other e9a pistolsI have also been converting some old autococker frames to use on some bulk co2 pistols based loosely on the vintage 111/112/115/116 pistols and I may use one on stubby as it'll allow me to shorten a valve by 20mm