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Thread: A possible game changer - Slugs for sub12 rifles - short review

  1. #106
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    BSA barrel twist is 1 in 18 i think so only marginally slower twist than LW
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  2. #107
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    Quote Originally Posted by Born Again View Post
    JSB are launching a 10.03 grain slug in 4.51 . It appears to have a deep base cavity, like a normal diabolo, the cynic in me wonders if it's drag stabilised too.

    https://www.facebook.com/17173571620...4084401971812/
    I have had a brief look at the JSB slugs. The meplat is much bigger and the base hollow has a number of disadvantages. Large meplats appear to be ok up to just over 50% of the diameter but over that there are large and sudden drag increases. The exact point at which the drag begins to increase is not clear but the JSB meplat appears to be above the values considered safe.

    Base hollows in projectiles cause problems with dynamic stability. The base hollow in the JSB slug will also move the centre of gravity forward causing a reduction in the aerodynamic moments leading to high stability factors which is bad for group sizes. This does not mean that the JSB slugs cannot group well but they may be more fussy of barrel sizes. The JSB slug looks a bit like a modified pellet with parallel sides and a slightly longer nose.

    Going by the JSB table of BCs the quoted BC is probably based on a high speed and the RA4 drag law. The RA4 is a totally inappropriate drag law for slugs.

    The slugs are not drag stabilised and neither are diabolo pellets. The only drag stabilised airgun ammunition are the old steel darts with tufts at the back.
    Last edited by ballisticboy; 13-05-2021 at 12:19 PM.

  3. #108
    Born Again is online now Owns three Roy orbison albums
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    Quote Originally Posted by ballisticboy View Post
    The slugs are not drag stabilised and neither are diabolo pellets. The only drag stabilised airgun ammunition are the old steel darts with tufts at the back.
    My bad.... apparently it's called "flare stabilised", this article seems informative, although who knows if it's accurate.

    https://hardairmagazine.com/ham-colu...lug-stability/

    This is interesting too,

    https://hardairmagazine.com/ham-colu...-miles-morris/

    You might be the author ? Or perhaps he is another member ?

  4. #109
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    Quote Originally Posted by Born Again View Post
    My bad.... apparently it's called "flare stabilised", this article seems informative, although who knows if it's accurate.

    https://hardairmagazine.com/ham-colu...lug-stability/
    Unfortunately Bob wrote that before I put him straight. Jim Tyler wrote an explanation of pellet aerodynamic stability in Airgun World, July 2019. There is also loads about stability in this series of threads.https://www.gatewaytoairguns.org/GTA...topic=169459.0

    Quote Originally Posted by Born Again View Post
    This is interesting too,

    https://hardairmagazine.com/ham-colu...-miles-morris/

    You might be the author ? Or perhaps he is another member ?
    Bob Sterne is a Canadian airgun enthusiast. I supplied the information.

  5. #110
    Born Again is online now Owns three Roy orbison albums
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    Thanks for the link, and some fascinating reading.

  6. #111
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    well, the 10.5 grainers didn't give any advantage for longer range accuracy in the two rifles I tested them in; a Rapid and an RM8, and coupled with the reduced ME, they are probably not a goer for these particular rifles.

    The rapid grouped 5/8" at 40 yards with JSB 8.4s, a fraction more with JSB 10.3s, and just over an inch with the slugs
    Similar story with the RM8, except both JSB variants were around 3/4", and the slugs were around 1 1/4"

    There was a very light breeze swirling around, but just the normal level that you expect in real world field conditions.

    My phoenix is actually a .22 (I forgot), but I do have another Rapid in .177 I'll test with, although it has a tightish choke so probably not idea for a solid slug either.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  7. #112
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    Well it's not sounding too positive but hats of for the feedback. I suppose slugs are the ammo of the fac guys.

  8. #113
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    Quote Originally Posted by Anothermiss View Post
    Well it's not sounding too positive but hats of for the feedback. I suppose slugs are the ammo of the fac guys.
    to be honest they weren't at all bad - way better than many "unsuited" pellets in the test rifles (e.g. 10 grain H&N Baraccuda - they were crap, and better than the JSB hades at 40 yards too). I think it's likely to simply be a case of pellets suiting the barrel, as with any pellet. However the slugs are probably going to be a bit fussier on barrel fit, due to not having a relatively flexible sealing skirt, and a solid body creating some friction.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  9. #114
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    Quote Originally Posted by Shed tuner View Post
    to be honest they weren't at all bad - way better than many "unsuited" pellets in the test rifles (e.g. 10 grain H&N Baraccuda - they were crap, and better than the JSB hades at 40 yards too). I think it's likely to simply be a case of pellets suiting the barrel, as with any pellet. However the slugs are probably going to be a bit fussier on barrel fit, due to not having a relatively flexible sealing skirt, and a solid body creating some friction.
    Thats pretty much it, in a nutshell Jon.
    Just like pellets, some rifles will get on with them better than others

    The ones that do, really seem to do well with them.

    There's a good video been put on Youtube by Notts Pest Control. Whacked a load of rabbits and corvids with them.
    No pass through either.

    I think he'd tried them in one rifle and they weren't too clever, but then he put them through a Daystate with great results. Mag fed too.

    Regarding that Rapid and the choke, I'd give em a whirl if you have any left. The choke on my LW barrel doesn't affect them and the hollow nose should allow a little constriction from an over tight choke.
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  10. #115
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    Old thread I know, but just an update on this... I got a new (to me) MFR barrel in .177 and tested out the Mako 10.5 slugs.
    With a moderate breeze they got 1" groups at 45 yards. The preferred pellets are QYS, which normally do around 5/8" to 3/4" groups at this range, but yesterday, in the same conditions, were also at 1". So that's a decent result... When I get chance I'll downrange chrono them through this barrel.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  11. #116
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    Quote Originally Posted by Anothermiss View Post
    Well it's not sounding too positive but hats of for the feedback. I suppose slugs are the ammo of the fac guys.
    Well they were pretty dire in my FAC as well

    I think you need a barrel designed for them, with no choke & maybe even a different twist rate.

  12. #117
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    Quote Originally Posted by Shed tuner View Post
    When I get chance I'll downrange chrono them through this barrel.
    I will only be impressed if you use a combro

  13. #118
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    Quote Originally Posted by tinbum View Post
    I will only be impressed if you use a combro
    NP. I have a 5mm steel plate, just need to drill an 8mm hole though and make sure it's very carefully aligned

    Now where's Robin's number.....
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

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