4x26mm port ? Taking that down to 3.0 should give another 1-2 FP just like that !
+10mm on the stroke and you'll be way over....
with a 28mm bore, synth seal, and a 3.0 port, a piston weight around 250-270g should work well. with leather, I'd say the 237g current weight=defo too light. syth and the original 4.0mm port, it'd probably be perfect.
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.
Going from experience in changing HW35s from leather to synthetic I reckon it'd be slammy with a synthetic seal and a 4mm port, Jon.
+10 on the stroke is just a note of the Max available with the cocking lever slots and geometry as standard, in real terms it would be unachievable because any stroke increase over 2mm would need the slot in the piston extending which would reduce that 10mm by a similar amount.
Using a Diana 28mm seal would take it upto about a 73.5mm stroke if needed, but it's a one hour round trip to buy one and I'm happy working at 71mm for now with an O ring.
All the best Mick
There's basically three reasons behind my thinking of using an O ring, Tone.
First off the piston isn't the best I've ever seen so making a bronze piston head with O ring will keep it centred at the front end.
Secondly, the leather piston seal is 8.5mm wide and the cocking lever slot has 3mm of clearance, so if I make the bronze head 6.5mm wide this still gives a 1mm cocking slot clearance and will increase the stroke to 71mm without messing about with the back end of the piston.
Lastly, bronze weighs more than steel per cc, so with a bronze piston head I'm adding weight to the piston without robbing any Spring room.
I may be going off in completely the wrong direction by increasing the piston weight but I reckon it's worth a punt --- I'll have a better idea which way to go when I've stripped and measured my ratting Mercury this morning.
All the best Mick
Good morning Mick,
After being initially slightly disconcerted drinking my morning coffee and reading of greasy balls I thankfully read on with interest!
I will be most interested to hear of your results with your experiments as I have a lovely 35s example giving low 10s in .22 which shoots great and seems as if its never been apart. But I've always wondered if it could be smoothed somewhat (bearing in mind how long that lube has been in there) and perhaps nudge power into low 11s.
It would be quite illuminating if you can arrive at a good performing 35 with power and accuracy something which Diana claimed it gave but sadly at least on power front it failed to deliver. My own thoughts were to go the route of perhaps a vortex or oem seal when I eventually get inside mine but I can see where you are coming from on the weight of piston and you may well be on to something good there.
Fingers crossed for you. I'll follow with interest.
Dave
Oooh look https://www.airgunbbs.com/showthread...Original-35-22
An unashamed plug. Is there no depth this fool will stoop to?
Founder & ex secretary of Rivington Riflemen.
www.rivington-riflemen.uk
I just took the barrel off and put the action in my lathe and wound it together with the tail stock.
Unfortunately after reassembly it won't cock --- bugger, but no big deal.
I've just had another quick calculation on Spring height. :-
Factory Spring 33 coils of 3.2mm wire = 105.6mm
New Spring 28 coils of 3mm wire + 16mm weight =100mm
So the spring looks good to go.
What I hadn't noticed before was that the rear of the piston pushes on the cylindrical sear that sets the trigger.
So although I'd cut the spring guide to a length I thought would be OK, I need to cut more off in order for the trigger to set.
I'll chop the guide and double check trigger operation without the spring in before I reassemble it again.
All the best Mick
Good idea.
I think that by upping the piston all up weight before you go anywhere else you will see the benefits (or otherwise) in increments. Only slight downside as we all know is the mere act of stripping the gun disturbs the lubes etc. Its near impossible not to disturb lubes on tasks like this.
Instinct tells me if you can improve things with the leather going synthetic will yield more improvements. However those with the leather fetish may (no, definitely, ) disagree
Dave
'leather fetish' ... 'greased balls' ... I think Ive clicked onto the wrong site (again. I. J - M. P for Oooop North) .
Founder & ex secretary of Rivington Riflemen.
www.rivington-riflemen.uk
Well after chopping an extra 10mm off the guide the gun cocks and fires so I ran it over the chrono. :-
image.jpg
I'm not happy with it though, and I'm quite happy to admit that I'm way out of my comfort zone using a leather seal.
I soaked the seal in Neatsfoot Oil while I was machining the weight and polishing all the internals, then I dried it off before reassembly.
Though most of the shots over the chrono with Superdomes are in the 585 - 600fps range, every now and then it'll fire at just under 300fps for a couple of shots and then go back up.
When it is running at the higher velocity it's fairly consistent either with or without a bit of smoke which is weird.
Now I know the age old advice with leather seals is to put a couple of tins of pellets through the gun until it settles down but life's too short for that, besides which I'm a tight git --- have you seen the price of pellets lately.
Anyway, I'm going to leave it alone for a day or two now while I think about it, as I still think I'd be happier using a synthetic seal or O ring as I know where I am with them.
Another thing I'm not happy with is the cocking stroke as the gun sounds like a bag of spanners --- I put this down to the awfull Spring guide and piston.
Apart from the above we're all good.
At least I now know why nobody bothered to tune these back in the good old days --- they're a right pain in the arse to work on.
All the best Mick
Agree with all the above, Mick.
And re your last comments, although I have no first hand experience, people's comments back in the day dissuaded me from trying to get acquainted..
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