More woes with my sumatra carbine :-(

[WILBA]

After tinners advice when my sumatra power locked last year i bought a predator hammer spring. After reassembly the gun was down on power but i knew how the adjust it to get the power up as it was only 9ftlb in the chrono but could not be arsed to stip it again so just used it for garden plinking fun. Gun had been working ok up until i last used it 3mths ago. Today pulled it out to use and the bugger is not firing again. Feels like it is power locked again. But why though as the pressure om rifle guage is on 190 bar which is fine. The hammer spring is not that old either. Plenty of heft in the spring as the gun is heavy to cock compared to the standard spring. Is this a common fault on the 707/sumartra rifles? At a loss what has caused this to happen again.

[rapidresponse1]

not good mate,i hope some one on here can help you out

[WILBA]

not good mate,i hope some one on here can help you out

Cannot understand it mste. The predator springs do not corrode so it cant be that. It was working a few months ago. Spring is plenty strong enough as it has been a bugger to cock as this spring is harder than the last.

[Shed tuner]

take the stock/ shroud off, remove end cap and spring, check power adjuster is not buggered.. or just unscrew the course threaded collar and remove. if it still won't fire get a large puch and a small hammer and the tap the vale stem directly.

[WILBA]

take the stock/ shroud off, remove end cap and spring, check power adjuster is not buggered.. or just unscrew the course threaded collar and remove. if it still won't fire get a large puch and a small hammer and the tap the vale stem directly.

If it is the valve stem what could have caused it to happen? Maybe it was not the hammer spring last time then jon? Would fitting the uprated valve stem cure it if it is the valve stem jon?

[Shed tuner]

need to see what the problem is first.

if the valve stem is getting stuck, it could be the profile of the mushroom head, somehow settling into and jamming into the valve face itself. But that would be unnusual, unless it's been previously modified, or made from a dodgy batch.. the material is delrin like. Maybe it could save some grease of something sticking in there ? Or an excessively heavy valve return spring. It's quite weird.. see if a few taps frees it up first.

Then again, maybe it could be as simple as a bent stem.. trouble is, if the stem was that bent, I wouldn't expect the head to seal. and those stems are thick / heavy duty as standard.

Puzzling.