HW35 Fettling

[T 20]

The front section with the concentric bands is solid metal, ie way more metal up front than on other pistons.
.

That bit looks like it came off a Dalek's top antenna.

I think I'd have made that extension out of alloy or Delrin to cut the weight down --- thinking about it I have a standard LGV and MK3 TX in my piston box, I'll go weigh them.

I take it that the extension is needed to put the rear bearing section in the correct location for the HW80 cocking shoe ?

[Shed tuner]

I take it that the extension is needed to put the rear bearing section in the correct location for the HW80 cocking shoe ?

that's my guess too Mick.. when I proptotyped up my 24mm HW80 using a TX piston, it neeed nearly an inch of nose extension for the piston skirt to sit right for the "in the groove" HW cocking shoe...

[Waddy]

That bit looks like it came off a Dalek's top antenna.

I think I'd have made that extension out of alloy or Delrin to cut the weight down --- thinking about it I have a standard LGV and MK3 TX in my piston box, I'll go weigh them.

I take it that the extension is needed to put the rear bearing section in the correct location for the HW80 cocking shoe ?

I don't think it's an extension as it's about 5mm shorter than the standard LGV piston in that comparative pic I found, which is explained by the shorter TX piston seal.



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[T 20]

I don't think it's an extension as it's about 5mm shorter than the standard LGV piston in that comparative pic I found, which is explained by the shorter TX piston seal.



.

Don't say I've got to go back over the workshop and measure them now.

I've only just weighed them --- TX mk3 piston 232gm, LGV piston 252gm

I had the idea that Bigtoe used the LGV piston with no extension but gained clearance on the shoe by cutting the shoe down a little ?

[Waddy]

Don't say I've got to go back over the workshop and measure them now.

I've only just weighed them --- TX mk3 piston 232gm, LGV piston 252gm

I had the idea that Bigtoe used the LGV piston with no extension but gained clearance on the shoe by cutting the shoe down a little ?

This LGV piston is running the TX piston seal so it's at least 5mm shorter. The shoe looks standard but I might be mistaken.


I have ordered a new B r it TX seal & breech seal


I think I'll have to work out which Titan spring it is too.

[TonyL]

So, I thought I'd have the 35 out yesterday for a quick session and zero check with the May Boinger Bash just around the corner.

The rifle seemed to have gone a little too "sharp" again. Minimal sight picture disturbance, to be fair, but feeling a little sharp, but not harsh. But after about 60 shots my fingers were tingling.

Groups were inconsistent. Some very tight. Some weird opening up. I used RWS Hobby, Suoerdome and FTT. The Hobby performed the worst.

Now, when I'd initially stripped it I wanted to address the slight vertical play in breech lock up. I ground the end off the latch. On a "dry build" this seemed to have worked, but on building the gun completely a little play was still evident. For the next build I fitted a new latch. It's the same. I wonder if the profiles of the latch as compared to the cut-out in the cylinder don't match?

Possibly apply epoxy to fill any gap there and see if it helps?

At the end of the session I got the chrono out.....a smidge under 690fps with the 11.9 grains Hobby for 12.5ft.lbs. Consistency was very impressive, however......0.8fps maximum variation over 5 shots! So I'm going to shorten the soring further. I'm wary of going too far as it's about flush with the end of the cylinder, but I'd rather have a nice, safe & legal and smooth shooting 10.5-11 than anything naughty.

We'll try and shoehorn some unexpected tinkering time in and see how it goes.

Any tips on the vertical play?

[Shed tuner]

with the preload getting that low, you might want to consider an alternate, softing spring Tone ? Worth trying before chopping this one...

[TonyL]

Cheers for that, Jon.

The thought had already crossed my mind. But the main downside to fitting other springs instead of kits for people like myself without lathes to make guides and top hats would be the resulting lack of refined manners. This spring has already been shortened twice. Happy to shorten further and I could always replace some active spring for washers if preload was critically low?

A TX spring would be lovely. But guessing not enough oomph? Although that might be okay with the seemingly very good efficiency?......

[Shed tuner]

Cheers for that, Jon.

The thought had already crossed my mind. But the main downside to fitting other springs instead of kits for people like myself without lathes to make guides and top hats would be the resulting lack of refined manners. This spring has already been shortened twice. Happy to shorten further and I could always replace some active spring for washers if preload was critically low?

A TX spring would be lovely. But guessing not enough oomph? Although that might be okay with the seemingly very good efficiency?......

nah, TX spring much too soft for a 35. you want at least 3.2mm guage wire.

[Waddy]

The trouble with testing a rifle with Hobbys is that they are so fast that almost any rifle that sits well under the limit with any ordinary domed pellet will be over with them.







.

[Mach 1.5]

Tony I'll bring my 35 to the bash for you to have a go with. Running a 21 coil old school venom thick coil vmach spring. Mach 1.5