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Thread: Extending piston

  1. #1
    Join Date
    Sep 2012
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    Extending piston

    As I’ve found decent changes with these SS nose jobs, I now want to try doing it the longer piston route to see if that longer spring room is any better as claimed.

    Id like to ask if I could be pointed towards anyone who could cut and weld an extension to this 400 piston keeping it straight and safe, one thing I don’t have is anyone welding stuff. I wish I could load an image to show what’s needed, but it’s either a section of piston or just the latch pad

    Chris
    If it ain’t broke, fix it till it is

  2. #2
    Join Date
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    Ah, yes, I think I can picture it. I hope you can find someone who might be able to assist.
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  3. #3
    Join Date
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    For that type of welding, I’d suggest laser welding, as that can be used with precision and doesn’t cause excessive heating to one side and pulling things over. If both sections mated perfectly with a slight bevel on the outer edge, orbital welding is a possibility.

    Carrs Welding in Kettering are excellent. They are also used to dealing with firearms welding repairs.

    https://carrswelding.co.uk/services/

  4. #4
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    are these rodless pistons ?

    If so, might be easier to cut the piston in half thru the centre, and then weld in a tubular piece in the middle, retaining the "interesting" freatures front and rear. Then just machine out the cocking slot and smooth out the weld joints.

    Much less to go wrong doing it that way...
    Last edited by Shed tuner; Yesterday at 05:10 PM.
    Always looking for any cheap, interesting, knackered "project" guns. But not lathes. I have too many lathes. Thanks, JB.

  5. #5
    Join Date
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    Quote Originally Posted by Shed tuner View Post
    are these rodless pistons ?

    If so, might be easier to cut the piston in half thru the centre, and then weld in a tubular piece in the middle, retaining the "interesting" freatures front and rear. Then just machine out the cocking slot and smooth out the weld joints.

    Much less to go wrong doing it that way...
    That's what I'd do too. The middle part of piston skirts tend to be a slightly smaller diameter than the front & rear. I think a decent welder could weld something like that, just needs spot welding at 12, 6, 3 & 9 o'clock to keep it straight. May need a quick spin in a lathe to take any excess weld off afterwards.

    Adding another latch hole rear of the skirt would be the simplest solution, but would the metal used be hard enough not to wear extremely rapidly ?

    .

  6. #6
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    Sep 2012
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    Thanks lads

    The piston has an extended latching pad which I thought I could just trim off and add another section to extend it, or cut piston inbetween the cocking slot end and the end of the piston so both welds were much bigger contact areas.

    Cutting middle of piston would work too and need the cocking slot cut through added piece and the welded up so as cocking arm pushed piston back far enough to latch, my only issue there is trying to clean up the inside that far down ?

    I’ve another piston to chop up if needed or just add the extra bit to existing latching pad so it’s just one small weld
    If it ain’t broke, fix it till it is

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