Diana Model 27

[Ciaran07]

The Idiots Guide is a sticky at the start of the Collectables forum ... where you are now. Look for the first post in the forum. It now runs to a lot of pages. We keep it for information on stripping old rifles not for general chatting so please do not use it for posting general posts. There is an index to the various guns included.

Cheers, Phil

Cheers bud I found it
if i take out the pin does it need to be put back in after
From memory I believe it’s got like rounded head do I just drill that off so it can be drifted
it will more and likely make sense when it’s apart again but thought it was best to ask about this pin before destroying the screw
Also is the mainspring I’ve got which is for the g27 ok ?

[Phil Russell]

The mainspring: I do not know exactly so can only suggest you try it for fit and see. Check the spring fits inside the piston with a not tight fit. If you have to push it into the piston it is too tight. A bit of a loose fit is OK but you must check that the spring guide also fits the spring .. again you should not have to force it; too tight is not good. You can get away with a slightly loose fit but may get a boing .. but this can be reduced by using a piston liner ... maybe home made from a beer can.
Regarding the piston head. I do not know as I have not done one. Does the rivet go all the way through the head i.e. can you see the pin from both sides? I am getting the impression that the pin has a domed head. If it is domed both sides you could try filing off one dome and then using a punch to drive the rivet out. It must be there to stop the piston head screw from coming loose so must be removed before the screw will undo to release the washer. If you can drift it out, you could put it back but if the head screw can be tightened well then you should be OK without it ... just check that the pin does nothing else other than pass through the head. I do not think it does. Of course, if you put it back, the hole in the screw must line up with the pin.
Cheers, Phil

[Ciaran07]

The mainspring: I do not know exactly so can only suggest you try it for fit and see. Check the spring fits inside the piston with a not tight fit. If you have to push it into the piston it is too tight. A bit of a loose fit is OK but you must check that the spring guide also fits the spring .. again you should not have to force it; too tight is not good. You can get away with a slightly loose fit but may get a boing .. but this can be reduced by using a piston liner ... maybe home made from a beer can.
Regarding the piston head. I do not know as I have not done one. Does the rivet go all the way through the head i.e. can you see the pin from both sides? I am getting the impression that the pin has a domed head. If it is domed both sides you could try filing off one dome and then using a punch to drive the rivet out. It must be there to stop the piston head screw from coming loose so must be removed before the screw will undo to release the washer. If you can drift it out, you could put it back but if the head screw can be tightened well then you should be OK without it ... just check that the pin does nothing else other than pass through the head. I do not think it does. Of course, if you put it back, the hole in the screw must line up with the pin.
Cheers, Phil

Cheers Phil for taking the time for your reply there’s some good points I will take onboard
I’ve fitted a few springs and tuning kits in the past so I’ve got a good idea of what kind of fit I’m looking for and to try and reduce twang saying that this rifle at best is not a power house so can’t see there being to many noises I’m more concerned about over spring the rifle but as the spring I’m getting is for the g27 I feel it should be alright the length is slightly smaller but thicker Wire
The piston seal didn’t look great shape last time I looked and I think I put a mk1 meteor spring in which worked but was only producing 450 FPS with Jsb 8.44
I’ve got an Australian 25mm parachute seal conversion kit on order most probably few people would cringe but hopefully should last

[Phil Russell]

No problem. I forgot to mention last time that I expect that if a new piston head was needed then a new screw would have been used and a hole drilled for a new pin.
Don't forget you can tweek power a bit with preload.

Here are spring measurements from a pre-war 27 I have recently corrected: 38 coils, 2.7mm, 12.8 - 13.0 id. This gave me about 40mm of spring to compress before engaging trigger block coils. Old spring was identical in measures but bent and collapsed.
Cheers, Phil

[Ciaran07]

New spring arrived today the seller sent me

DIANA / ORIGINAL 27 19 13 3 245 Ox

Instead of the cobham one I mentioned earlier
I stripped the rifle put new spring in it was flush
With the end of cylinder so the length of the trigger mechanism to preload it about
2” at a guess
Now the fun starts I had an old drift pin knocking about so cut that to hold the two parts of the trigger block back retaining the smaller soft spring with this in place old jumper over the barrel and pushed down then drifted the proper pin through easier said than done didn’t change piston seal yet

With old spring was doing 450fps 8.44gn
New spring doing 620fps 8.44gn