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Thread: More Airsporter help please

  1. #1
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    More Airsporter help please

    Hi all
    Can anyone shed any light on a problem I’m have with a BSA airsporter MK1/2 the piston will not latch with the trigger mechanism. It seems not to have enough travel while operating the cocking lever.
    If I remove the piston from the cylinder and manually insert it into the trigger block it engages ok. I have noticed a previous owner has cut off some of the threads that screw in to the cylinder, presumably to allow the piston to travel further in to the trigger block. This method works fine on the bench but when the gun is reassembled the cocking mechanism does not provide enough travel to engage the trigger.
    I don’t know if the gun worked before I took it apart as I didn’t check, but I can’t see how it would as I have only replaced worn parts.
    Any help appreciated.


    Phil

  2. #2
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    spring too long? too many washers in front of/behind the spring?

    I seem to remember an issue with an airsporter once that was allowing too much play on the cocking lever producing these symptoms........ and I have seen old airsporters with a few mm ground off the front of the trigger guard to allow extra stroke as well. look for ovalled holes in the linkage, (it seems to be coming back to me now!)

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    Essential to use a standard Airsporter spring!


    ASM
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    Quote Originally Posted by philcbr View Post
    Hi all
    Can anyone shed any light on a problem I’m have with a BSA airsporter MK1/2 the piston will not latch with the trigger mechanism. It seems not to have enough travel while operating the cocking lever.
    If I remove the piston from the cylinder and manually insert it into the trigger block it engages ok. I have noticed a previous owner has cut off some of the threads that screw in to the cylinder, presumably to allow the piston to travel further in to the trigger block. This method works fine on the bench but when the gun is reassembled the cocking mechanism does not provide enough travel to engage the trigger.
    I don’t know if the gun worked before I took it apart as I didn’t check, but I can’t see how it would as I have only replaced worn parts.
    Any help appreciated.


    Phil
    Take the mainspring out and try cocking the gun then. If it does not cock or only barely cocks, then it sounds like the piston is worn on the cocking slot and may need welding a little. You can try leaving the cocking lever off and move the piston back with a rod/ screw driver etc. If it engages with the trigger ok then the piston can move far enough back (doing it this way) and that would also sugget the cocking slot.
    If the piston engages ok without the spring in, then it sounds like like the mainspring is too long and the gun is coilbound.
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  5. #5
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    Quote Originally Posted by ggggr View Post
    Take the mainspring out and try cocking the gun then. If it does not cock or only barely cocks, then it sounds like the piston is worn on the cocking slot and may need welding a little. You can try leaving the cocking lever off and move the piston back with a rod/ screw driver etc. If it engages with the trigger ok then the piston can move far enough back (doing it this way) and that would also sugget the cocking slot.
    If the piston engages ok without the spring in, then it sounds like like the mainspring is too long and the gun is coilbound.

    I was just going to say the same, Guy.

    I had a MK1 last month with the same problem :-

    http://www.airgunbbs.com/showthread....15#post7185915




    All the best Mick

  6. #6
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    I had a mk3 airsporter that wouldn't cock when I got it. It turned out the trigger adjustment had been wound all the way in and that was preventing it cocking. Long shot but might be worth checking

  7. #7
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    Thank you all for your helpful suggestions.
    I have purchased a standard main spring from one of the well-known suppliers. The spring has the same number of coils and the wire thickness is the same as the old one so I'm guessing this is not the cause of the problem.
    My concern centres on the fact some of the thread has been removed from the part that screws in to the cylinder. It seems to me if that had not been performed the piston would not travel far enough into the trigger block to latch the main sear? Are the pistons from the MK1 and mk2 the same dimensions?
    I have tried putting the gun back together minus the spring, pushing the piston by hand does not engage the main sear also.
    I have inspected the pivot points and the piston and do not see any appreciable wear with the contact points, at least not to my inexperienced eye.
    When operating the cocking lever it travels to its fullest extent limited only by the stud that is screwed in to the cylinder.
    I am including links to some pictures that might better illustrate my situation.

    http://i513.photobucket.com/albums/t...psmnxx9kx7.jpg
    http://i513.photobucket.com/albums/t...psd9o5ytwa.jpg
    http://i513.photobucket.com/albums/t...pssqonuhuc.jpg

    Once again thanks for any suggestions or solutions that might be forthcoming.
    Regards
    Phil

  8. #8
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    Is the trigger/sear spring installed correctly ?

    Baz
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  9. #9
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    Quote Originally Posted by philcbr View Post
    Thank you all for your helpful suggestions.
    I have purchased a standard main spring from one of the well-known suppliers. The spring has the same number of coils and the wire thickness is the same as the old one so I'm guessing this is not the cause of the problem.
    My concern centres on the fact some of the thread has been removed from the part that screws in to the cylinder. It seems to me if that had not been performed the piston would not travel far enough into the trigger block to latch the main sear? Are the pistons from the MK1 and mk2 the same dimensions?
    I have tried putting the gun back together minus the spring, pushing the piston by hand does not engage the main sear also.
    I have inspected the pivot points and the piston and do not see any appreciable wear with the contact points, at least not to my inexperienced eye.
    When operating the cocking lever it travels to its fullest extent limited only by the stud that is screwed in to the cylinder.
    I am including links to some pictures that might better illustrate my situation.

    http://i513.photobucket.com/albums/t...psmnxx9kx7.jpg
    http://i513.photobucket.com/albums/t...psd9o5ytwa.jpg
    http://i513.photobucket.com/albums/t...pssqonuhuc.jpg

    Once again thanks for any suggestions or solutions that might be forthcoming.
    Regards
    Phil
    Something is wrong with that trigger in the photograph. The main sear should be sitting lower under the force of the trigger spring acting at the back end and the vertical sear bearing surface should be higher than and in front of the main sear. Don't have a photo of how it should be at the moment, but yours is definitely not right.

    P.S. Found a pic of how it should look before cocking here
    P.P.S. You have not secured your Photobucket, so all your photos are available to be viewed. You eed to set your album(s) to 'Private' if you don't one anyone else to browse through them.
    Last edited by Airsporter1st; 30-03-2017 at 08:49 AM.
    Happy Shooting!! Paul.
    "We cannot solve our problems with the same thinking that we used when we created them" - Albert Einstein.

  10. #10
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    Yes, the sear is too high blocking the piston from latching. Somehow the spring is not exerting enough pressure upwards.

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

  11. #11
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    Thank you all again for taking the time to suggest solutions to my problem.
    I have reassembled the trigger as it came to me when I got the gun. I’ve uploaded more pictures that better show the trigger components as assembled by me.
    It seems to function as a trigger ok but not latch due to insufficient travel of the piston in to the trigger block, sorry if I’m repeating myself in this matter but I can’t see how it would have worked even before I got it.
    More pictures.

    http://i513.photobucket.com/albums/t...psnixh5cjt.jpg

    http://i513.photobucket.com/albums/t...psmcdqprgo.jpg

    regards
    phil

  12. #12
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    Quote Originally Posted by philcbr View Post
    Thank you all again for taking the time to suggest solutions to my problem.
    I have reassembled the trigger as it came to me when I got the gun. I’ve uploaded more pictures that better show the trigger components as assembled by me.
    It seems to function as a trigger ok but not latch due to insufficient travel of the piston in to the trigger block, sorry if I’m repeating myself in this matter but I can’t see how it would have worked even before I got it.
    More pictures.

    http://i513.photobucket.com/albums/t...psnixh5cjt.jpg

    http://i513.photobucket.com/albums/t...psmcdqprgo.jpg

    regards
    phil
    The trigger certainly looks right now, anyway.

    No idea what is wrong now, but there must be a reason! Can you take a similar picture to the first one, but with the piston rod fully inside the trigger block to its maximum depth?
    Last edited by Airsporter1st; 30-03-2017 at 06:52 PM.
    Happy Shooting!! Paul.
    "We cannot solve our problems with the same thinking that we used when we created them" - Albert Einstein.

  13. #13
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    Piston polishing

    How much did you polish the underside of the piston where the cocking lever sits? I had this problem where around 1mm had worn away. This then caused it to not latch fully when cocking as the lever could not push the piston back far enough before it hit a barrier. If the gun was doing this already it might explain why they removed threads to try and make up the difference. However I fixed it by welding a couple of mm back on to the underside of the piston. It was surprising how that slight worn down area caused the issue. You can test this by placing something in to create a gap and testing the movement without the spring in to see if it latches.

  14. #14
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    Hi all

    as requested more pictures added.
    While polishing the piston I did not do the end of the rod that inserts in to the trigger block, it does not have any noticable wear marrks on the end.

    http://i513.photobucket.com/albums/t...pswuqbdecn.jpg

    http://i513.photobucket.com/albums/t...psu09r4vzm.jpg

    I will assemble the gun tomorrow minus the spring and try suggestions from the group.

    Regards

    Phil.

  15. #15
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    Not the rod I meant the groove in the piston itself, mine had worn away so not allowing the rod to push the piston the whole distance it needed to travel.

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