hw 80 help

[mallyally]

I have recently bought a mk 1 hw80 in 177 its in realy good nick but the power is low 650 fps
i am sure I have enough spring pressure but the piston seal is very tight , I also realize that if I ask ten different people the question I will probably get twelve answers !
But here we go how tight should the piston seal be in the cylinder ?
did weiraugh make different cylinder bore / piston heads in the early ones ? cos this one is really tight
cheers for any advice (i am fairly sure this is causing my power problem )

[TonyL]

Mmmm....most have problems keeping the power of the 80 low enough.

Check the breech seal first.

If that's okay then, depending how tight the piston seal is, may well be your problem. Is it a new seal? If so, what make? I'm not aware that HW ever did any different sizes. You may just have a smaller diameter cylinder than the norm, but it's not something I've come across, personally. If yours is ever so tight, try and re-size (carefully) and see how it goes. If it's a new seal, it might just be worth banging plenty of shots through it, periodically checking the velocity, and see how it goes.

I actually prefer to let them "run themselves in" if not silly tight, as you do hear many, many reports of sized seals wearing out early.

[p.sharp]

I'd be temoted to either size the seal or shoot it in. I buttoned my piston (which made the piston tight) pre-loaded up to 11ftlbs which rose to 16 once 'shot in'

[mallyally]

I have replaced the breech seal only, The piston seal came with the gun ! I think I would need to shoot a few million pellets to bed this one in I am afraid .
I have a few old heads somewhere and will try one of those in the week rather than taking any material off the one in the gun

[gibboj]

like someone said before you have a problem keeping 80`s under 12 ft lbs it sounds like the piston head is way to tight and the more you shoot it the tighter it will go due to thermal expansion [heating up and dragging even more] ,theres only one size seal for the 80 [30mm] .the seal should be a nice push fit down the comp tube with your finger or something similar . if it a bit looser its not a problem as the parachute type will open up slightly as air is trapped infront of the seal causing the lips to expand .id be tempted to size the seal or try one of your others and when it sized or a nice fit in the comp tube it will only take a couple of days to bed in rather than a couple of month`s
atb john

[keithy]

If the power has not increased noticeably after one tin of pellets you may have a problem, it will still continue to rise for about four tins as was my experience.

[Maxiboy Wales]

I have recently bought a mk 1 hw80 in 177
i am sure I have enough spring pressure but the piston seal is very tight

how can you tell the condition of a spring in a secondhand gun.. have you had it apart and measured the spring or looked to see if its straight

[maximus]

I have just fitted one of the new type washers to my .177 80, if anything it was slack, if you feel like splashing out this could be the best way to go.
got mine off chambers. Seems to be working ok so far.

regards

Max

[mallyally]

how can you tell the condition of a spring in a secondhand gun.. have you had it apart and measured the spring or looked to see if its straight

Yes I have had it apart three times now , changed the piston head the last time for an old one and the power has gone up
Although I could tell that the spring was healthy form the cocking effort and lack of noise on cocking

[mallyally]

I have just fitted one of the new type washers to my .177 80, if anything it was slack, if you feel like splashing out this could be the best way to go.
got mine off chambers. Seems to be working ok so far.

regards

Max

I think that's probably my next move I bought the breech washer from chambers and am now kicking myself for not getting a piston head at the same time although to be honest it looks fine

[Pat Murphy]

I have recently bought a mk 1 hw80 in 177 its in realy good nick but the power is low 650 fps
i am sure I have enough spring pressure but the piston seal is very tight , I also realize that if I ask ten different people the question I will probably get twelve answers !
But here we go how tight should the piston seal be in the cylinder ?
did weiraugh make different cylinder bore / piston heads in the early ones ? cos this one is really tight
cheers for any advice (i am fairly sure this is causing my power problem )

I've come across the same problem, but in 22 in my HW80.

I've measured the inside dia of the piston chamber, & it's 30mm, but the piston seal is 31mm. Refitting the piston with the seal it's extremely tight, & to work the piston I have to connect the barrel/linkage together.

PM.