Gecado (Diana) Mod. 22 in .177

[shaz_au]

Hi airgun enthusiasts, long time, no posts and all that!



This is second of those two air rifles I was gifted as part of a deceased estate. This one still functions but is in need of work. I believe it is over 50years old but I'm unsure how to date it. I do love how lightweight it is, it's super easy to cock and it's quiet. Over the chronograph with 7gr pellets (Meisterkugeln) most shots are around the 550fps but then you'll get a random one at 500fps or 680fps. It's got a serious patina over most of the metal work, really the only bluing still visible is hidden by the stock. I'm not going to be able to do anything about the metalwork. One day I might refinish the stock though.




I've ordered a new seal from custom air seals and started disassembly. The screw that holds on the existing leather seal seems seized pretty good. Does anyone have any tips on how to remove it and where I can and can't put force on the piston? can I put vice grips around the black piece or is this connected to the screw?



It looks like I'll need a new spring too, the picture doesn't do the bends in this thing justice! Does anyone know where I can source one locally? I don't want to over spring this, I'd like to keep it easy to cock, smooth and quiet.

[fenring]

My first air rifle.

Likely the piston head screw got peened a bit from dry firing - not uncommon on youth sized guns....

Spring - would be easier to just order from Chambers in the UK I think.




https://www.gunspares.co.uk/products/24368/22

[grmkc]

Been a while Shaz. I see you found your own train wreck, just like the HW30 I found a few year back. Had the same issues. I soaked the piston head in WD40 for a couple of days then used an impact driver. The leather piston seal just crumbled off on mine.

Converted the hw to a synthetic seal with kit available from Chambers or Customairseals.com.au in Vic. The plastic bit that the screw goes through keeps the leather seal in shape. Chambers should still sell the whole kit and kibodle. Conversion kit will come with screw, seal and adaptor. If you go leather, get the seal, plastic bit and new screw. You'll need to soak the seal for several days in neetsfoot oil. Customairseals.com.au should have spring as well.

[shaz_au]

Thanks for the replies guys! Yes, that synthetic seal kit is what I ordered from custom air seals, I couldn't see a spring to suit online and I didn't think to ask them, if I can't get it there then I'll use chambers as per your suggestion fenring.

I'm off to find the impact driver

PS I stuffed up my chrono readings, that's what happens when you try to do it memory. The average was about 350fps not 550! If it was 550 I wouldn't be touching it.

[fenring]

Don't forget to replace the breech seal.

[grmkc]

I have a box of springs in the workshop. I can see if there's a suitable one. Need the following info.

* length
* wire thickness
* OD & ID
* number of coils

We'll see what's in the box of tricks.

[shaz_au]

Awesome, more replies!
Well the impact driver worked, super easy and I only stabbed myself once, ouch!

Silly question: Does the pin in the side of the piston retain the top of the piston or the piston rod in the body? I noticed it was protruding slightly after removing the piston washer screw. After tapping it back in place I can actually see it protruding into the side of the threaded hole of the piston washer screw.


The new piston seal kit arrived today. Yes I forgot the breach seal fenring. I thought it was interesting there wasn't a breech seal on the barrel side, the truth is I haven't even looked on the compression chamber side of the gun where it apparently lives

Thank you very much for the kind offer grmkc, I'll take some measurements and get back to you.
Cheers guys!

[grmkc]

I would have though that the pin should sit flush. See how it sits with the new screw back in.

[shaz_au]

Hi grmkc,

The spring dimensions (in mm) are as follows:
- Outer Diameter: 16.8
- Inner Diameter: 11.9
- Wire thickness: 2.45
- Overall Length: 178
- Number of Coils: 30

Thanks!

[Chrispy]

from my experience of Diana rebuilds, get some wet/dry and polish the bearing surfaces to a glass like finish. i got mine to about an 800 grit before i was happy.

Then I smeared a fine layer of super moly grease over the surface as I assembled it. Changed the impulse and the action was silky smooth.

Just a thought.

Chrispy

[shaz_au]

Thread necro

Chrono 18/11/18
310.3
306.7
312.3
290.1
275.1
303.1
303.4
250.2
245.0
275.9

Lo 245
Hi 312.3
ES 67.24
SD 24.61

• It would appear the new piston seal did not help things.

• There is no breach seal and doesn't appear to be any sort of cutout for one, neither the barrel or receiver are marked. Unless it was just a super thin felt washer glued to one of the surfaces I don't see how one would fit.

• Meisterkugeln pellets seem quite loose in the breach, most could fall out of the breach again if the barrel was pointed skyward.

Maybe a Diana 21 Panther as an alternative to fill this option as a low powered, easy cocking, easy shooting, short overall length air rifle?

[shaz_au]

Barrel side:


Receiver Side:

[shaz_au]

So my own photo helped me, it just looked like a bit of goo stuck to the breach but there WAS a seal there.

[LWR58]

Those little 22’s can shoot really nicely

You need the leather seal
It acts like a wick and holds lubricant to let it lightly diesel with each shot
Without the dieselling these oldies will not perform

I can supply you with a Maccari spring

The breech seal is on the receiver side
It’s just a suitably sized O ring

It should do 500FPS with 7 gns

Hope this helps

Lewis

[shaz_au]

Hi Guys,
So the new breech seal didn't help, velocities got slower.
When I put the seal in, I put a piece of 50lb fishing line under the seal to help raise it up a bit and get a tighter seal, the instructions suggested copper wire. Dunno if this was the right thing to do as I'm not sure how much the seal is meant to protrude.

Anyway I pulled it down again, I noticed that the piston seal was able to freely rotate even with the piston bolt tightened down. It was loose enough to allow the piston to rotate but not move otherwise if that makes sense. I slightly shortened the bolt so when tightened down the piston seal was solid and won't rotate. If anything velocities seemed to drop again. Here is where we are currently at.

10 shots
Lo 164
Hi 236
Av 215.9
ES 71.94
SD 22.24

The spring is pretty shagged so I tried turning it around to ensure the spring guide straightened out as much of the bend as possible, didn't seem to help.

Gun seems to misfire regularly, can feel the sear release the spring, hear the air escape but the pellet doesn't move, solution seems to be to sit the pellet further into the barrel to engage the rifling which gets a better seal? I can't tell where the leaking air noise is coming from (breach or barrel). The noise probably lasts for over 1/2 a second though.

How much is a spring? I'm still wondering if I just swap the thing for a Panther 21 and be done with it...