HW77 Tuning

[dtdukok]

‘The difference to look at’ not ‘the difference in size’.

As in ‘is there I difference in profile or something else at first glance - without measuring them.

Muppets 😆

[bozzer]

I know ... but it was funny. Well ... tickled me.

Yours will be 25mm. A set of verniers will prove it. A 26mm seal in a 25mm tube is going to be silly tight and I can't see you getting 11fp with that set up.

Get her opened up and get that seal resized. Let us know how it goes.

[dtdukok]

It is 25mm and I have a pan of piston soup bubbling away on the stove now 👍

I’ll let it cool, clean it up and let you know.

Thanks,

Darren

[archie]

Surely if you try to resize the head in a drill the pressure of the abrasive paper will just stop the head turning whilst the piston turns ?

[bozzer]

Archie

Gently pressure and it works fine. The seal will continue to spin with the piston. If you try and grab it hard then yes the seal will spin on the piston head. Gentle ... and it's fine.

[dtdukok]

Or boil it apparently! All done, reassembled and now putting 11.7 fp out without the power washers.

Thanks to all, especially Bozzer 👍

Now going to scope it up and hand it back 😩

On the bright side though, now got a nice 97KT on its way to me!

I really appreciate all your help,

Darren

[TonyL]

There was a post on here where someone resized them a different way. They degreased, then fitted new seal. Then put piston ( with new seal ) inside comp tube. They then dropped the comp tube and piston inside a pot of boiling water and boiled the lot for about 10 mins. Then remove from water and allow to cool. Dry completely with paper and hair dryer. Apparently the seal is sized. I've not done this myself.
.

It is 25mm and I have a pan of piston soup bubbling away on the stove now 👍

I’ll let it cool, clean it up and let you know.

Thanks,

Darren

Or boil it apparently! All done, reassembled and now putting 11.7 fp out without the power washers.

Thanks to all, especially Bozzer 👍

Now going to scope it up and hand it back 😩

On the bright side though, now got a nice 97KT on its way to me!

I really appreciate all your help,

Darren

I think it may have been myself that posted that once (and I guess a few other people) after being told by that great 80s FT shooter, Mr Graham Henderson, a few years ago. Apparently, a fair few of the top '77 shooters did this back in the day, alleviating the need for abrasives and also sizing the seal perfectly and in one go.

Apparently, it will still wear more quickly than one that has just been "shot in", but many were more than happy to pull their guns to bits very regularly, so not a downer. And part of me also sorta thinks that the wear rate maybe should not be any higher as friction is reduced.

Hope your friend loves it.

[dtdukok]

Well it sounds a bit wacky but it worked a treat so thank you.

It’s literally made-to-measure now. If that means I need to do it for him again in a year or so then so be it for the price of a seal.

Thanks,

Darren

[deejayuu]

Ps, what’s the difference to look at between 25mm and 26mm seals?

Thanks,

Darren

looking at the back of the seal the hole for attaching to the piston boss is the same on both but the 26 mm has wider "land" around it

[deejayuu]

Surely if you try to resize the head in a drill the pressure of the abrasive paper will just stop the head turning whilst the piston turns ?

String wound tight betweeen the piston head and seal will lock it in place. Just don't forget to remove it after

[dtdukok]

looking at the back of the seal the hole for attaching to the piston boss is the same on both but the 26 mm has wider "land" around it

Thank you. They knew what I meant, just yanking my chain 😆

[Rickenbacker]

I'm still a bit surprised you needed the full length of that new spring...

So, about this 97KT you're expecting - I assume that's not going to be 25mm?

*sharp intake of breath* What's your plans with that one then?

[dtdukok]

I believe this 97KT to be about 5 or 6 years old so I expect it to be 26mm. Why do you ask?

My plans for it are to see what I’ve got when it lands. It may already be sorted, you never know. In which case: clean, polish, lube and reassemble. Then learn how to shoot it as well as I can.

But if it needs it, I’ll start thinking about a drop-in kit for it.

Full length of the new spring in the 77? - it didn’t need cutting and it’s not going over. Happy days.

Thanks,

Darren

[bozzer]

Hoorah ... result. Well done.

Tony

I think it was indeed you that informed us of the boil to size option. Cheers matey.

As you say, I don't think the resized ( boiled or otherwise ) should last much less than a shot in one. As it is now the right size there will be less friction so less wear, as you said. One could say that the overall life time is reduced slightly but most, if not all, of that will be the initial period of thousands of shots bedding in to size. Ten mins in the pan or several weeks and 40 quid's worth of pellets later. I'll go for Plan A.

Yup, you can lock the piston seal temporarily to stop it spinning whilst you resize with wet n dry and a drill. I like the idea that non fixed it's sort of self regulating. If you try and put on too much pressure at once then it spins and stops you taking too much off.