Theoben Rapid Forum

I've been tinkering with a mk4 trigger. Will be making new bushes for the sears.
Don't know whether a previous owner has made adjustments..honestly thought I'd bought a lemon. Still not sure ::)
The safety wasn't working properly when I first bought the block.. the spring and catch dog were butchered.

Looking at the top sear spring, tightening the retaining screw appears to be the only way to give the spring tension...essentially forcing it open with the countersink.

I made a parallel bushed screw (shown; just needs the thread shortening) to free up the coil and clear the trigger sear but the spring doesn't apply load.

Is the countersink / crushed loop correct?
Seems rather crap.

Yes...sort of....
The springs on all of my Mark 4s,
The loop on the srings are large enough not to be crushed by the countersunk of the screw.

Stuart

Thanks Stuart, I was rather hoping you'd reply, seem to remember you had made new bushes for one of your mk4s.
just didn't seem right with the countersink opening the spring like that.

Made individual brass bushes so that all of the sears are central to the cassette and the adjustment grubs now.
Middle sear twisted left, trigger went right.

I made the retaining screw/bush, obviously no good with the original spring.
So I made another sear spring from 0.5mm piano wire with a wider angle, more than one attempt  ;D  ;D
Thats free on the bush and has roughly the same load/torsion.

damn, gotta come apart again..noticed I put the safety spring relief facing up

Ah Yes....The life of Modding...
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/trig-bush.jpg)
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/trig-bush2.jpg)(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/trig-bush3.jpg)(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/trig-bush4.jpg)(https://photos.imageevent.com/scl_electronics/gun/air/websize/Mark4-tirg1.jpg)(https://photos.imageevent.com/scl_electronics/gun/air/websize/Mark4-tirg2.jpg)

Have Fun!!!
Stuart

Cheers Stuart, those pics were the inspiration. There was so much play in the delrin bushes combined with rough sears.
Not 100% happy yet, somebody had taken a file to the underside of the safety hook to clear the chewed up dog.
I'll attempt to make a shouldered grub out of silver steel as there is sill some movement in the blade.