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Thread: Airsporter piston jammed ?

  1. #1
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    Airsporter piston jammed ?

    Hi, recent new member here with a problem with my Airsporter.
    I posted on another thread re : airsporter woes, but thought it best to start my own.


    ...I bought my .22 Airsporter new in 1973. I doubt if 5000 pellets have been through it in all that time. About 6 months ago I re-discovered it (actually grandson found it in one of the bedroom cupboards along with my old HW35), so started a bit of target practice in the garden.
    With the Airsporter I probably fired off about 200 pellets and noticed the piston sticking, pull the trigger then gun fires after a slight delay, but then it got worse and the piston apparently jammed in the bore. The piston does gradually let go but doesn't fire. Prior to this malfunction I hadn't noticed any lack of power etc.
    So, how do I go about stripping the Airsporter to look for what's jamming the piston?
    The HW35 is still working ok, buts seems 'agricultural' in comparison to the Airsporter..and it's heavier.


    I've had a couple of useful suggestions, thanks for those, but don't want to but-in on the other thread.

    Allen

  2. #2
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    Hi you really should be in the Collectors corner to get the best answers as a few of us are into collecting Airsporters.

    Sounds like the piston backing washer has done the usual and swollen or collapsed and jammed it up.

    If you search the collectors corner threads there will be a few similar, as it is not uncommon on older BSA springers.
    BASC

  3. #3
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    The piston can jam through a couple of reasons. The nylon piston head can absorb moisture over a period of time and swell in diameter. Also the piston buffer washer can disintegrate and become all gooey through bacteria. There are a number of methods for getting the piston out. I use brute force with a hammer and drift on the piston cocking slot. Others use chemicals and heat. I skim the piston head down and refit it, and make a new buffer washer.

    Baz
    Last edited by Benelli B76; 27-07-2017 at 05:58 AM.
    BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD

  4. #4
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    Quote Originally Posted by DEAN C. View Post
    Hi you really should be in the Collectors corner to get the best answers as a few of us are into collecting Airsporters.

    Sounds like the piston backing washer has done the usual and swollen or collapsed and jammed it up.

    If you search the collectors corner threads there will be a few similar, as it is not uncommon on older BSA springers.
    Looking there now....that lot's going to take some reading, but I'm on with it....loads of info.

    Allen

  5. #5
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    Had same prob with a BSA Mercury Mk1 lately, had to tap piston out using a drift on slot in latch rod (now polished back up!). The gun had, like yours, shot normally, maybe slightly slow lock time on reflection, then suddenly refused to cock. Luckily the rough young owner appears not to have bent the barrel in his efforts!
    A Soldier's time is spent in distress and danger, or in idleness and corruption.
    HW80K, HW35, BSA Lightning XL, BSA Mercury Mk1

  6. #6
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    Quote Originally Posted by Benelli B76 View Post
    The piston can jam through a couple of reasons. The nylon piston head can absorb moisture over a period of time and swell in diameter. Also the piston buffer washer can disintegrate and become all gooey through bacteria. There are a number of methods for getting the piston out. I use brute force with a hammer and drift on the piston cocking slot. Others use chemicals and heat. I skim the piston head down and refit it, and make a new buffer washer.

    Baz
    That appears to be a common theme running through the posts I've read through. I'm trying to get my head around the tricky bit of getting the trigger assembly (I think that's what it's called) off the gun.

    Allen

  7. #7
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    Quote Originally Posted by wints View Post
    That appears to be a common theme running through the posts I've read through. I'm trying to get my head around the tricky bit of getting the trigger assembly (I think that's what it's called) off the gun.

    Allen
    I have done a lot of these in the last few months. The trigger assembly usually comes off easily in 80% of the cases but you can get some very tight ones. Disconnect the cocking lever linkage to the trigger block so it is free to unscrew from the compression tube. Try and unscrew it using a bit of leverage through the aperture where the trigger and sear are pinned, you may have to give the lever a few taps with a hammer to shock it free. If it does not shift you may have to apply a little heat to the steel compression tube. Also use any type of penetrating spray oil you may have. As you unscrew be careful of spring tension being released.

    Baz
    BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD

  8. #8
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    Quote Originally Posted by Benelli B76 View Post
    I have done a lot of these in the last few months. The trigger assembly usually comes off easily in 80% of the cases but you can get some very tight ones. Disconnect the cocking lever linkage to the trigger block so it is free to unscrew from the compression tube. Try and unscrew it using a bit of leverage through the aperture where the trigger and sear are pinned, you may have to give the lever a few taps with a hammer to shock it free. If it does not shift you may have to apply a little heat to the steel compression tube. Also use any type of penetrating spray oil you may have. As you unscrew be careful of spring tension being released.

    Baz
    That will work, but its better to use a suitable lever through the round hole in the block, just forward of the trigger/sear apperture, which is provided for the specific purpose - much less risk of damaging the trigger assembly.
    Happy Shooting!! Paul.
    "We cannot solve our problems with the same thinking that we used when we created them" - Albert Einstein.

  9. #9
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    Wints/dalesman917 - same here on a Mercury Mk1. Rather than face the same effort of a repeat job in future, I didn't bother to skim the head in the lathe, I replaced it with aluminium head. My Mk1 which I bought very cheap, was in very good condition externaly and no slop in the breech jaws and curiuosly, it is very consistent and very accurate since the rebuild - I was going to sell it on, but, I'm keeping it!

    Meant to have added, used a Meteor O-ring: 3/4" X 1/8"......
    Last edited by SRV1; 27-07-2017 at 11:43 AM. Reason: Spelling and further comment

  10. #10
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    Once the nylon has been "water conditioned" it will not swell any further in future. Nylon products that have to work to close tolerances should be water treated before final sizing. This apparently was not carried out by BSA hence the legacy of seized piston heads

    Baz
    BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD

  11. #11
    look no hands's Avatar
    look no hands is offline Even better looking than a HW35
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    This is why I always recommend stripping down any Airsporter or Mercury as soon as you get it to see what condition the innards are in, I do it every time with mine, for the sake of £20/30 it save a hell of a lot of aggro trying to remedy it when it's jammed up.

    Pete
    Far too many rifles to list now, all mainly British but the odd pesky foreigner has snuck in

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