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Thread: Diana Model 27

  1. #1
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    Diana Model 27

    Good evening all can anyone please tell me the measurements for a mainspring for a Diana model 27 the year made is 1938.
    Kind regards
    Ciaran

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    27 spring

    MAKE MODEL OD mm ID mm WIRE mm LENGTH mm COILS SOURCE
    DIANA / ORIGINAL 27 19 13 3 245 Ox
    DIANA / ORIGINAL 27 18.8 13.4 2.7 285 Versandhaus

    From the very useful guide under heading of classic airgun strips.
    Not sure if that refers to both pre & post war Dianas, but no doubt someone else will!

    HTH

    Bru
    Last edited by laverdabru; 19-11-2020 at 06:53 PM. Reason: noticed date
    Webley Mk3 x2, Falcon & Junior rifles, HW35x2, AirSporter x2, Gold Star, Meteors x2, Diana 25. SMK B19, Webley Senior, Premier, Hurricane x 2, Tempest, Dan Wesson 8", Crosman 3576, Legends PO8.

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    Cheers I have this spring would it do it’s very similar

    DIANA / ORIGINAL G27 19.5 13.2 3.15 220 34 Cobham

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    Ah, didn't see that further down
    No doubt some who knows a great deal than me can tell you. I've only had post war ones.

    Sorry

    Bru
    Webley Mk3 x2, Falcon & Junior rifles, HW35x2, AirSporter x2, Gold Star, Meteors x2, Diana 25. SMK B19, Webley Senior, Premier, Hurricane x 2, Tempest, Dan Wesson 8", Crosman 3576, Legends PO8.

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    Also can anybody advise me on correct removal of the piston leather seal

    Am I right in thinking there’s s pin to be removed first is this a case of drifting thru

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    Can anyone assist with advice please

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    The 27s I have seen, the pre-warquarter stock versions (only a wooden butt like the BSA Standard) have the piston seal held by a screw (maybe 2BA? or 5mm?) through the washer into the end of the piston. The washer can take a few forms ... I have mostly seen leather cup washers with a central hard disc countersunk for the fixing screw but have also seen just two leather discs, each c 3mm thick instead of the cup washer, but again having a countersunk washer for the retaining screw.
    I do not have experience of the later (newer) mod 27 but believe it too had a leather cup washer held by a screw.
    Note: the early 27s have a very basic trigger while the later 27s could well have the feared Diana 3 ball version.
    There will be a strip guide to the early 27 in 'Idiots Guide' posts 73, 74, 136. Later 27 is post 123.

    Cheers, Phil

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    Quote Originally Posted by Phil Russell View Post
    The 27s I have seen, the pre-warquarter stock versions (only a wooden butt like the BSA Standard) have the piston seal held by a screw (maybe 2BA? or 5mm?) through the washer into the end of the piston. The washer can take a few forms ... I have mostly seen leather cup washers with a central hard disc countersunk for the fixing screw but have also seen just two leather discs, each c 3mm thick instead of the cup washer, but again having a countersunk washer for the retaining screw.
    I do not have experience of the later (newer) mod 27 but believe it too had a leather cup washer held by a screw.
    Note: the early 27s have a very basic trigger while the later 27s could well have the feared Diana 3 ball version.
    There will be a strip guide to the early 27 in 'Idiots Guide' posts 73, 74, 136. Later 27 is post 123.

    Cheers, Phil
    Cheers Phil the version I’ve got 1938 is what I’d call full stock I believe the type that Milbro acquired the rights to build after the war but don’t quote me on that I just noticed last time it was apart that there was what looked like a drift pin near the piston seal and thought it had to be removed before trying to undo the screw in the back of my mind I think I’ve read in the past someone not doing so and chewed the screw up

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    OK ... a bit more research leads me to think you are correct ... it seems that some 27s, maybe those made in Germany, indeed did have a pin to hold the piston washer screw in place and advice was to drill it out. See Idiots Guide posts 7,8, 10

    Chambers show the Original 25 that has the pin. If the pin goes though to the other side there should be no problem, if it only goes in one way then drilling it out may be the only option?
    Cheers, Phil

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    Quote Originally Posted by Phil Russell View Post
    OK ... a bit more research leads me to think you are correct ... it seems that some 27s, maybe those made in Germany, indeed did have a pin to hold the piston washer screw in place and advice was to drill it out. See Idiots Guide posts 7,8, 10

    Chambers show the Original 25 that has the pin. If the pin goes though to the other side there should be no problem, if it only goes in one way then drilling it out may be the only option?
    Cheers, Phil
    Cheers phil I’m unaware of these idiot post maybe because I am one where you I find them

    Cheers

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    Quote Originally Posted by Ciaran07 View Post
    Cheers phil I’m unaware of these idiot post maybe because I am one where you I find them

    Cheers
    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

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    Quote Originally Posted by Phil Russell View Post
    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 ?
    Last edited by Ciaran07; 22-11-2020 at 05:33 PM.

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    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

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    Quote Originally Posted by Phil Russell View Post
    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

  15. #15
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    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
    Last edited by Phil Russell; 23-11-2020 at 10:42 AM.

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