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Thread: An interesting bore stroke question...

  1. #1
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    An interesting bore stroke question...

    If someone somewhere was contemplating building a new break barrel springer and wanted to sell it in the U.K., Europe and the US with the bore/stroke/power level optimised for each of those markets.....

    Clearly for such a gun to be commercially viable the minimum number of market specific parts would be critical, if we assume the barrel, breech block, back block, stock, trigger and potentially iron sights would have to remain common....

    Is it conceivable that 3 different cylinder and piston units could be designed to be dimensionally identical externally yet bored to suit the 6, 12 and 30ft/ib markets, in the manner of the various reduced bore HW80 conversions?

    Guns could then be assembled and finished according to their market without having effectively three totally separate sets of parts or compromising everything in a single product...

    There must be a flaw with this somewhere gentlemen?
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    I don't know the science exactly but the bore ought to be bigger on the big 'uns and smaller on the small ones to be efficient. I suppose you could sleeve the cylinder and work it like that but the smallest one would be too big ....

    Probably works easiest with the sliding-chamber fixed barrel system. But even then, you end up with overweight guns. Even the HW77 25mm could have been made 7/8ths size and not lose performance.

    I like the HW range, they have a rifle for every circumstance!

    Shed Tuner is the man to answer this one, he knows about esoteric things like 22mm pistons and that....

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    I'm going through a similar exercise at the moment and the short answer is, no.

    For argument's sake let's say the UK version is 25mm bore and the magnum US version is 30mm bore. The UK version would basically end up like a sleeved down HW80 and the first thing everyone will say is - just get an hw99

    When you start putting an idea down on paper (or in CAD) you very quickly realise the compromises that manufacturers have to make to please the majority.

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    Quote Originally Posted by RichardH View Post
    If someone somewhere was contemplating building a new break barrel springer and wanted to sell it in the U.K., Europe and the US with the bore/stroke/power level optimised for each of those markets.....

    Clearly for such a gun to be commercially viable the minimum number of market specific parts would be critical, if we assume the barrel, breech block, back block, stock, trigger and potentially iron sights would have to remain common....

    Is it conceivable that 3 different cylinder and piston units could be designed to be dimensionally identical externally yet bored to suit the 6, 12 and 30ft/ib markets, in the manner of the various reduced bore HW80 conversions?

    Guns could then be assembled and finished according to their market without having effectively three totally separate sets of parts or compromising everything in a single product...

    There must be a flaw with this somewhere gentlemen?
    You're going to have quite a thick liner for 6 to 30ft-lb. That would get quite heavy. Stroke could change as well.

    Think of it another way. If you already have a barrel, breech block, back block, stock, trigger and potentially iron sights already, then the only change you need to make is the cylinder and stock. The stock needs to be made anyway and with CNC changing that isn't a big deal and you'd be working with just in time anyway so what's the issue? Same as making lefties.

    I'm not sure the problem is the design of the rifle. I think the problem is the market appetite (not an internet forum's) vs the amount of pennies a rifle needs to be manufactured for. I'm not even convinced manufacturing costs are a majority factor in the price of a rifle anyway these days.

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    Airsoft have been doing that for a while. I had an ICS M4 about 10 years ago, on which the powerlant was interchangeable very easily. I had 2, one for full auto and one for single shot, because the rules meant faster speeds for single shot than for auto.
    It basically was as you say, the spring, piston and compression tube were all self contained.

    I think If this idea were to be floated for airguns, there would be a lot of lost volume inherent to the design whatever it may be, so that should be compensated for.

    https://www.fire-support.co.uk/produ...rbox-d-bore-up

    These are available with heavier springs and larger bore compression tubes
    Donald

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    This could be done reasonably easily on a sliding breech rifle like a '77. Just machine the slide differently and put in a piston with a different head and different length internal rod.

    Or do what Dianna do and put a washer in the breech. It makes a horrible jumpy gun.

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    One other major factor that so far no one has mentioned is that to produce in sufficient volumes to satisfy each market and make it a viable proposition the manufacturer would have to have seperate production lines for each version. Assembly costs on an already labour intensive product might not make it viable.

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    Quote Originally Posted by RichardH View Post
    If someone somewhere was contemplating building a new break barrel springer and wanted to sell it in the U.K., Europe and the US with the bore/stroke/power level optimised for each of those markets.....

    Clearly for such a gun to be commercially viable the minimum number of market specific parts would be critical, if we assume the barrel, breech block, back block, stock, trigger and potentially iron sights would have to remain common....

    Is it conceivable that 3 different cylinder and piston units could be designed to be dimensionally identical externally yet bored to suit the 6, 12 and 30ft/ib markets, in the manner of the various reduced bore HW80 conversions?

    Guns could then be assembled and finished according to their market without having effectively three totally separate sets of parts or compromising everything in a single product...

    There must be a flaw with this somewhere gentlemen?
    Hi Richard, I think Walther have done this approach with the century and LGV. Personally I would not go for as wide a power range and use a 25mm bore altering the stroke to go fac or the other way, 3 different piston latch rods. I am drawing up a break barrel (slowly!!) that will use TX piston, trigger group and stock. Not looked at it for a few weeks but I was only thinking of 12 ft lbs version anyway.
    Plinkerer and Tinkerer

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    Yeah, Walther LGV & century.. the later is a full 30mm, the former the same gun sleeved down to 25.

    Add a longer piston rod for 6Fp with the sleeve and you have 6 Fp covered. Job done.

    More like 20 FP max though, but that's just a stroke issue. Build the gun with a longer cylinder, and longer stroke in the 30mm version becomes easy.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

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    I'm not sure 30ft lbs is a good idea in a springer. I would of thought early 20's is as far as is comfortable?
    Plinkerer and Tinkerer

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    The answer must be a Diana 460!

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    Quote Originally Posted by Shed tuner View Post
    Yeah, Walther LGV & century.. the later is a full 30mm, the former the same gun sleeved down to 25.

    Add a longer piston rod for 6Fp with the sleeve and you have 6 Fp covered. Job done.

    More like 20 FP max though, but that's just a stroke issue. Build the gun with a longer cylinder, and longer stroke in the 30mm version becomes easy.
    Quote Originally Posted by maximus View Post
    I'm not sure 30ft lbs is a good idea in a springer. I would of thought early 20's is as far as is comfortable?
    And I would be thinking in exactly the same direction as the above.

    And fully agree with the maximum power expectations if a nice, usable firing cycle is desired.


    Or just go, say, 26mm with three different length latch rods (and maybe 17/18 ft.lbs)?
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    Having said that, and taking into account WonkyDonky's "Taming the HW80 my way" thread, maybe an updated HW80 with piston bearing would do us nicely, with the stroke from just over 50mm upwards. And 20+ ft.lbs easily achievable with the longer stroke. Wouldn't take much work, either......
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  14. #14
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    Quote Originally Posted by TonyL View Post
    Having said that, and taking into account WonkyDonky's "Taming the HW80 my way" thread, maybe an updated HW80 with piston bearing would do us nicely, with the stroke from just over 50mm upwards. And 20+ ft.lbs easily achievable with the longer stroke. Wouldn't take much work, either......
    Very true but I thought that when this was discussed a while back, we all wanted a light to medium weight rifle (something to better the 99 in theory), so a sleeved down HW80 size gun would limit the market as well.

    Like what's already been mentioned and what Bigtoe once said, all it needs is a different length piston rod and that's a lot of the problems solved, for not a lot of money either (about an extra 50p worth bit of metal according to Tony) and everything else (apart from the spring and a top hat may be) can stay the same, thus reducing costs even more and all the person on the assembly line has to do is choose between three different pistons to what ever power model they are assembling at the time, all the manufacturer has to do then is to make the agonising decision whether or not they want to undo all their fine engineering work by adding fishtail checkering to the stock

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

  15. #15
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    If it's such a good idea then why isn't it being done. After all it's a competitive market, why not get one over on your competitor?

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