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Thread: Airsporter RB2 tune

  1. #121
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    Sounds like either wrong piston, or wrong cocking slide/link.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  2. #122
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    Quote Originally Posted by Shed tuner View Post
    Sounds like either wrong piston, or wrong cocking slide/link.
    I'd bet it's the piston as there is physically nowhere else for the linkages so go in either direction. If the slot in the piston was further forward (deeper skirt), then it would strike the cocking lug when fired. But when the piston is at rest it's too far forwards and the link can't be fitted. I've put a wanted post in the Collectable section....

  3. #123
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    OK it's a very long shot, but have you called Protek just to see if they know where there might be one?
    Cheers, Phil

  4. #124
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    The thing is, what other BSA would of had that diameter of piston with a central rod? I can't think of any.
    Plinkerer and Tinkerer

  5. #125
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    Quote Originally Posted by maximus View Post
    The thing is, what other BSA would of had that diameter of piston with a central rod? I can't think of any.
    me neither, but it could be from a completely different gun. IIRC they are 29mm bore, like the supersport (I know these don't have a central rod). Didn't webley also use this diameter ?
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  6. #126
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    Quote Originally Posted by Shed tuner View Post
    me neither, but it could be from a completely different gun. IIRC they are 29mm bore, like the supersport (I know these don't have a central rod). Didn't webley also use this diameter ?
    The piston seal fits in the same way as the Superxxx range, the Webleys were the other way round, ie; Bsa have female pistons, Webley are male. Also, all the modern Webleys (from Hawk/Vulcan onwards) have a slot on the bottom of the piston for the sear to engage with, not a rod.

    I've just bought an HW77 compression chamber, maybe I'll beat Shed tuner to the sliding breach conversion. Or it may go in my Eclipse.......

  7. #127
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    Quote Originally Posted by Oddbob08 View Post
    I've just bought an HW77 compression chamber, maybe I'll beat Shed tuner to the sliding breach conversion. Or it may go in my Eclipse.......
    quite likely, as I'm about 5,000 miles away from my garage at the moment, keeping away from Covid lockdowns.
    Besides my health and sanity, and much nicer weather, another plus is I get to play with my 20 FP pro Elite after a few years break - what a gun
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  8. #128
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    Airsporter RB2 tune

    Quote Originally Posted by look no hands View Post
    The lump at the bottom of the piston is where the rod is attached to the piston, I had to build up the space around that lump so that the delrin top hat could sit on a flat surface, regarding the adjustable transfer port, I was once told by Tony Wall at SFS that he used to back the screw out so the TP was fully open and then tune the rifle from there, apparently you can then us less spring.

    Pete
    That's what i did to mine it shot much nicer & was without a doubt the most accurate & powerfull airsporter i ever shot. I'd still have it if it wasn't for dratted tennis elbow.

  9. #129
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    Quote Originally Posted by Shed tuner View Post
    quite likely, as I'm about 5,000 miles away from my garage at the moment, keeping away from Covid lockdowns.
    Besides my health and sanity, and much nicer weather, another plus is I get to play with my 20 FP pro Elite after a few years break - what a gun
    Lucky son-of-a-gun....

    Typing of the 77, I've had a few over the years (first one way back when they were the new kid on the block in 1983 or 4, cost £115 from Adams in Darlington...long gone now ) and a few TX200s too, and one thing I thought they all needed was a seating nipple on the transfer port, can't quite remember what Jim Tyler found when he experimented with pellet seating, but thought it would save my thumb. But back to the idea of the sliding breach arrangement, BSA did exactly that with the Goldstar (the original rotary magazine spring gun, not that old two wheeled thing or the new wind in the tank thing they do now). Shame there are no spares available, though I suspect if the Goldstar uses the same piston washer as the others in their Superxxxx range, then it stands to reason the outer cylinder must be bigger to house the compression chamber and one wouldn't fit the RB2.

  10. #130
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    yeah, the goldstar has a pretty fat cylinder, I think 28 or 29 mm bore. Mine has also long since gone.

    Ref the seating nipple, I did experiment with a transfer port sleave on TX that was left deliberately slightly protruding, such that it woudl seat the pellet ~0.75mm into the bore. It was very consistent, but did cost me a bit of power - I think it was too deep; something like a 0.3mm protrusion would probably be good.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  11. #131
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    look no hands is offline Even better looking than a HW35
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    Quote Originally Posted by Shed tuner View Post
    yeah, the goldstar has a pretty fat cylinder, I think 28 or 29 mm bore. Mine has also long since gone.

    Ref the seating nipple, I did experiment with a transfer port sleave on TX that was left deliberately slightly protruding, such that it woudl seat the pellet ~0.75mm into the bore. It was very consistent, but did cost me a bit of power - I think it was too deep; something like a 0.3mm protrusion would probably be good.
    It might even be around the 30/31mm mark, I remember stripping one many years ago and the piston came out the main body tube without having to remove the maxi grip rail (which you can't do with the Superstar), the pistons seem to be different (according to Chambers) but the piston seals are the same part number for the Supersport/star and Goldie, which means 29mm, so the inner compression tube must add a couple of millimetres to the total.

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

  12. #132
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    Quote Originally Posted by look no hands View Post
    It might even be around the 30/31mm mark, I remember stripping one many years ago and the piston came out the main body tube without having to remove the maxi grip rail (which you can't do with the Superstar), the pistons seem to be different (according to Chambers) but the piston seals are the same part number for the Supersport/star and Goldie, which means 29mm, so the inner compression tube must add a couple of millimetres to the total.

    Pete
    yeah, I meant the actuall compression tube, so 29mm makes sense. must be at least 1mm wall, so 31mm ID for the action tube, which in turn would be at least 1.5mm wall, so 34mm OD at a guess ? Big beastie.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  13. #133
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    Well I was toying with the idea of sleeving down my Eclipse cylinder, that's something like 30mm id, and I have a spare piston to use, does anyone know of a good source for the tubing? If someone can make them to my dimensions that would be even better.

    I'm also at the point where the piston I have for my RB2 is going to get cannibalised for bits to make a new piston using a spare Superxxxx piston, a lot of drilling, swearing and things being thrown across the shed.......

  14. #134
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    i use various matal suppliers on e6ay. seamless hydro tubing.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

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