I really like my LGV, bought second hand, which I resolved to keep to original spec. But my usual philosophy kicked in -its working perfectly, so what can I do to improve it - so when I read Jim Tyler's article in last months AGW (Jim Tyler's articles being probably the only reason I keep reading AGW to be honest) I couldn't keep my hands off it. New TX Mk III original spring from Chambers (brilliant service, ordered lunch time, arrived next morning) and half an hour later (including a degrease and sparing re-lube) the spring was in with 36mm preload (quite a lot of washers) which Mr Tyler said gave him 11.3 ft lbs. My chrono check said 6.4 fpe, so I added washers to give 40 mm preload, which Mr Tyler said gave him "far too close to the legal limit", and the gun wouldn't cock!
It took my almost octogenarian brain a few days to work out that this was because all the extra washers meant that the top hat was contacting the guide and limiting the travel of the latch rod so, next I took 5mm off the rear guide (easy job in a woodworking lathe, using woodworking turning tools) and with 40 mm preload the gun cocked, but energy only went up to 7.8 ft lbs. Walther spring back in and 22mm preload gives 10.4 fpe.
Has anyone else tried this, and if so with what result please? Or, can any one of the hundreds of people who know much more about the spring gun than I do please suggest why this "simple tune" might work for Mr Tyler, but not for me?