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Thread: BSA double sear project, latest progress, new questions.

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  1. #1
    Join Date
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    BSA double sear project, latest progress, new questions.

    An update at last on this project, I have started a new thread as it has been a few weeks since it dried up, link to original below if a catch up is needed.

    http://www.airgunbbs.com/showthread....rigger-problem

    To recap I needed a piston and double sear unit for this project as the gun came with a botched piston rod and double sear.

    The end notch on the rod had been removed and the front lobe(?) of the sear had been cut right down no doubt to become single sear but was the one that should have been left alone hence no latching as no surfaces mate up.

    I searched the normal known parts outlets, and this forum for the parts and a sear showed up on here.
    I had the chance to borrow a piston of a double sear type for measuring how to cut a new rod to fit to my piston.
    The borrowed piston was from a shorter cylinder gun but the rod pattern was all we needed. Careful measurements taken to work out where the rod notches need to be for latching at the correct point of full cocking.

    Then it turned out the new sear was also worn and filed such that it would not be able to latch on the new rod and the answer was to build up the profile on each sear with weld, re shape to match the rod notches and case hardened afterwards.

    New pics show the parts & trial assembly

    https://imgur.com/gallery/tsBo4R7

    Next concerns are:
    When setting the trigger guard screws nice and tight the trigger locks up but is Ok if they are not made tight??

    It lacks power so original spring and leather washer in question. Power is such that it won't fire Ely Wasps but will fire (at low velocity) Milbro Caledonian.
    The Wasps are tight through the loading tap (when trialled out on the bench) at 5.56 & the Caledonians are not so tight at 5.55, I think I recall wasps are good for BSA's but maybe not early guns? Especially if power is low.
    So I have a working gun at this pint but will knock over feathers more than cans
    Steve

    I've had Good deals & great info from many in this forum.

  2. #2
    Join Date
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    2,267
    Thanks for the update. An interesting thread, and I wish you the best of luck getting this rifle back up to full health.

    Lakey

  3. #3
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    Location
    weymouth
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    Quote Originally Posted by stevegv8 View Post
    An update at last on this project, I have started a new thread as it has been a few weeks since it dried up, link to original below if a catch up is needed.

    http://www.airgunbbs.com/showthread....rigger-problem

    To recap I needed a piston and double sear unit for this project as the gun came with a botched piston rod and double sear.

    The end notch on the rod had been removed and the front lobe(?) of the sear had been cut right down no doubt to become single sear but was the one that should have been left alone hence no latching as no surfaces mate up.

    I searched the normal known parts outlets, and this forum for the parts and a sear showed up on here.
    I had the chance to borrow a piston of a double sear type for measuring how to cut a new rod to fit to my piston.
    The borrowed piston was from a shorter cylinder gun but the rod pattern was all we needed. Careful measurements taken to work out where the rod notches need to be for latching at the correct point of full cocking.

    Then it turned out the new sear was also worn and filed such that it would not be able to latch on the new rod and the answer was to build up the profile on each sear with weld, re shape to match the rod notches and case hardened afterwards.

    New pics show the parts & trial assembly

    https://imgur.com/gallery/tsBo4R7

    Next concerns are:
    When setting the trigger guard screws nice and tight the trigger locks up but is Ok if they are not made tight??

    It lacks power so original spring and leather washer in question. Power is such that it won't fire Ely Wasps but will fire (at low velocity) Milbro Caledonian.
    The Wasps are tight through the loading tap (when trialled out on the bench) at 5.56 & the Caledonians are not so tight at 5.55, I think I recall wasps are good for BSA's but maybe not early guns? Especially if power is low.
    So I have a working gun at this pint but will knock over feathers more than cans

    Hi Steve,

    I may have a 1 1/8" (28mm) BSA piston seal knocking about somewhere, will look a bit later and let you know but if I have you can have it FOC if it's any good to you.
    blah blah

  4. #4
    Join Date
    Dec 2015
    Location
    Banbury
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    417
    Quote Originally Posted by DCL_dave View Post
    Hi Steve,

    I may have a 1 1/8" (28mm) BSA piston seal knocking about somewhere, will look a bit later and let you know but if I have you can have it FOC if it's any good to you.
    That'll be nice, I'll wait and see if you find it, thanks
    Steve

    I've had Good deals & great info from many in this forum.

  5. #5
    Join Date
    Dec 2007
    Location
    weymouth
    Posts
    2,988
    Hi Steve,

    Sorry for delay. Right, I found a 28mm BSA cup seal/washer looks a little rough but your welcome to it, or give me a few days and I'll knock some up...(I thought I had some in the box but I have given a few away on t'other side recently and now seem to have ran out...)

    Same as for t'other chap though, if you want some bits of leather to make one yourself your welcome to some.
    blah blah

  6. #6
    Join Date
    Dec 2007
    Location
    weymouth
    Posts
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    PM sent
    blah blah

  7. #7
    Join Date
    Aug 2004
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    Quote Originally Posted by stevegv8 View Post
    An update at last on this project, I have started a new thread as it has been a few weeks since it dried up, link to original below if a catch up is needed.

    http://www.airgunbbs.com/showthread....rigger-problem

    To recap I needed a piston and double sear unit for this project as the gun came with a botched piston rod and double sear.

    The end notch on the rod had been removed and the front lobe(?) of the sear had been cut right down no doubt to become single sear but was the one that should have been left alone hence no latching as no surfaces mate up.

    I searched the normal known parts outlets, and this forum for the parts and a sear showed up on here.
    I had the chance to borrow a piston of a double sear type for measuring how to cut a new rod to fit to my piston.
    The borrowed piston was from a shorter cylinder gun but the rod pattern was all we needed. Careful measurements taken to work out where the rod notches need to be for latching at the correct point of full cocking.

    Then it turned out the new sear was also worn and filed such that it would not be able to latch on the new rod and the answer was to build up the profile on each sear with weld, re shape to match the rod notches and case hardened afterwards.

    New pics show the parts & trial assembly

    https://imgur.com/gallery/tsBo4R7

    Next concerns are:
    When setting the trigger guard screws nice and tight the trigger locks up but is Ok if they are not made tight??

    It lacks power so original spring and leather washer in question. Power is such that it won't fire Ely Wasps but will fire (at low velocity) Milbro Caledonian.
    The Wasps are tight through the loading tap (when trialled out on the bench) at 5.56 & the Caledonians are not so tight at 5.55, I think I recall wasps are good for BSA's but maybe not early guns? Especially if power is low.
    So I have a working gun at this pint but will knock over feathers more than cans
    I have had Imp Mod D’s with a loop of ancient plumbers twine in the end of the block. Which was obviously a period or even factory fix. This may cure the sloppy fit of the block into the cylinder which may be the source of your trigger guard screw problems.
    "helplessly they stare at his tracks......."

  8. #8
    Join Date
    Dec 2015
    Location
    Banbury
    Posts
    417
    Quote Originally Posted by silva View Post
    I have had Imp Mod D’s with a loop of ancient plumbers twine in the end of the block. Which was obviously a period or even factory fix. This may cure the sloppy fit of the block into the cylinder which may be the source of your trigger guard screw problems.
    I don't have a sloppy fit as such although when tight the block does go a fraction past the "home" position, backed off a fraction so the screws will thread it's all fine unless I set them as tight as the ought to be. ??
    Steve

    I've had Good deals & great info from many in this forum.

  9. #9
    edbear2 Guest
    Quote Originally Posted by stevegv8 View Post
    I don't have a sloppy fit as such although when tight the block does go a fraction past the "home" position, backed off a fraction so the screws will thread it's all fine unless I set them as tight as the ought to be. ??
    Really daft question, but have you done them up with the block off and looked down the spring guide to make sure they are not a fraction too long ?.....these screws can strip and can be replaced with 2BA screws, if done well this is hard to spot and obviously the replacements can be longer.

    If you measure them and post on here people could tell you if the correct length.

    ATB, ED

  10. #10
    Join Date
    Dec 2015
    Location
    Banbury
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    Quote Originally Posted by edbear2 View Post
    Really daft question, but have you done them up with the block off and looked down the spring guide to make sure they are not a fraction too long ?.....these screws can strip and can be replaced with 2BA screws, if done well this is hard to spot and obviously the replacements can be longer.

    If you measure them and post on here people could tell you if the correct length.

    ATB, ED
    I will look into that, also update on my post above, the block actually threads in by just less than a quarter turn past the central position when tight so is backed off some amount for fitting trigger guard and screws which then lock the trigger when they are tight, so will look into their length.
    Steve

    I've had Good deals & great info from many in this forum.

  11. #11
    edbear2 Guest
    Quote Originally Posted by stevegv8 View Post
    I will look into that, also update on my post above, the block actually threads in by just less than a quarter turn past the central position when tight so is backed off some amount for fitting trigger guard and screws which then lock the trigger when they are tight, so will look into their length.
    Hi Steve,

    It's quite common for the blocks to rotate past the lining up point, 1/4 turn seems quite a lot but have seen similar.

    ATB, Ed

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