hw80 transfer port and short stroke.

[97nick]

Hi folks, I am in line to inherit a nearly new HW80, which I want to short stroke with Tinbums piston head, giving the piston a polish and keeping the original spring.
the gun is .177, should I do anything with the transfer port size? cheers.

[threelander]

i have fitted the short stroke head on a few 80,s never needed to mess with the TP

[97nick]

Hi folks, I am in line to inherit a nearly new HW80, which I want to short stroke with Tinbums piston head, giving the piston a polish and keeping the original spring.
the gun is .177, should I do anything with the transfer port size? cheers.

got the gun, its lovely
recoil is quick and a bit twisty. it twangs as usual.

placing the rifle on a box and taping a pen to the butt makes a consistent recoil traces of 8.5mm, note this is with no scope and gun is .177. I will fit Tinbums short stroke this weekend and run the test again. I will also crono the gun before doing anything to it, but it does not feel to be over the limit at all. it should be very nice once the twang is away and the short stroke is fitted

[97nick]

got the gun, its lovely
recoil is quick and a bit twisty. it twangs as usual.

placing the rifle on a box and taping a pen to the butt makes a consistent recoil traces of 8.5mm, note this is with no scope and gun is .177. I will fit Tinbums short stroke this weekend and run the test again. I will also crono the gun before doing anything to it, but it does not feel to be over the limit at all. it should be very nice once the twang is away and the short stroke is fitted

striped the rifle down and de-greased. its a very nice spring, and a good fitting guide as standard. quite a bit of pre-load, but this is probably a good thing to keep piston bounce down?
any way fitted a home made spring sleeve from a plastic milk bottle, and the short stroke extension. the gun is now super smooth to cock and fire, a quick thump of recoil but very clean and quick. doing the recoil test now shows 6.25mm so a reduction of 2.25mm. no crono test yet as the gun needs to settle in, but it sounds and feels like 10.5 flbs.
it is shooting light and heavy pellets with no problems which is great. will update with the crono test as soon as I can get it done, hopefully I can trim the spring a bit to make it even nicer.

I would highly recommend the extension!

[97nick]

did the test, it comes out at 10.8ftp with JSB's perfect!
it will probably rise a little as it beds in fully, so will keep an eye on it.
next job is the pellet test, I have JSB Exact, H&N FTT, RWS Superfields and Bisley magnums.
SARC's shoot this weekend so will see how it does with a scope on it, then take it back off again for the Open sight shoot on the 20th. I want to use heavy pellets for that as the range is shorter, so hope the bis mags work well.
at the moment getting 20mm edge to edge groups at 25yrds with open sights.

[TonyL]

Sounds excellent, Nick.

Enjoy.