Discussion in 'Piston & Spring' started by dozbadthebad, Jun 14, 2017.
Have fun!, and preferably book the sessions with the shrink now.... the joys of shooting springers
Interesting thread, makes me want to buy one.
don't do iT
All you need do is search for how many are losing 1 to 2fpe after 5 to 6 months of ownership of an LGU, then ask them to measure the spring length or ask how many have suffered broken springs...its lots.
You can actually order LGU comp tubes with a larger port right from the factory, however its still not large enough IMO. Consider the port is shorter than the TX port, and yet 2.6mm in diameter stock UK spec, what they are doing is forcing the pressure up to level out soft and hard pellets energy by running a small port and over springing the gun, only issue with that is it acts just the same as shooting heavies from a springer, eventually is shags the spring up. Short stroke, over spring, and test with superdomes and superfields etc...you will see the same effect.
There is no need for the port to be any less than 3.6mm for the UK, infact the port could come right out to 4mm and the SCR is still high enough to shoot a 25mm stock piston without a pelllet but a reset spring and it will not crash harshly, although i would not advise doing it obviously. Nick you must have shot a Diana 52 T06 at some stage with the 2 or 2.5mm restrictor, my last one had a 2.5mm restrictor, it rattled every filling out my head. I retried that restrictor back in a 25mm converted gun running 85mm stroke with a converted LGU piston, full bearings, the vibration had gone but it needed way more spring to deliver 11fpe than with the port restrictor gone, recoil reduced with it gone as did surge...the D52 with seal has a similar port length to the LGU.
I actually built and tested a 160g LGU 25mm skirtless set up just 3 weeks ago and started at 2.8mm port and worked up, i could feel the piston bounce at 3mm, even mildly at 3.4mm, i was dialling in preload with the smaller ports and resetting the preload to lower input energy and maintain the same power output as i enlarged the port, when i hit 3.6mm the magic happened. 4 hrs wasted titting around to just be sure i got it right when i first experimented when the LGU first came out. This was with a very soft spring btw, a stock spring 1 coil shorter is almost as good but has stiffer cocking as has a stiffer rate.
AA got the dia right with the TX mk2, they just got the length of the port wrong.