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Thread: Slug / airbullet development 2005 to present.

  1. #1
    MOT: Thomson Pneumatic Rifles

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    Default Slug / airbullet development 2005 to present.

    It would seem that slugs have come of age and it time to dust of some dies and build some new ones!

    A bit of background;

    The first slugs I designed where around 2005 when I became interested in pushing shots beyond the 70 meter mark. The only drawback then was that the only caliber that was readily available was .177/4.5mm. My tuned AR78 was capable of hitting 10/10 9mm spent cases at 75m (I could usually only manage 9/10 )

    The next best caliber was .20/5mm and I set about designing quite a few doodled prototypes. Only two survived but the issue then was funds and equipment. The best equipment came from the US and there were about 4 to 6 month waiting periods, combined with the fact that you could buy 500 pellets for about R25 for reasonable stuff and about R35 for JSB/ Air arms! Times have changed!

    On returning to Natal in 2006 I was able to buy 5 .20cal barrels from an ARF forum member Boondock, another .20cal fan. Shortly after acquiring these barrels I started on a high-power .20cal build for another ARF forum member Fox. We were working to 80+fpe and there were no commercial pellets that would get anywhere near there. So I set out to design a projectile that would give accuracy and power in .20 caliber. The design moved from a spritzer boat tail into its final form of the FMG (FOX MAY GERONI) after the three participants in the rifle build. A second rifle was build at the same time for 44flbs using the 21in barrel and 24.4gr Eunjin pellets.


    Images shows rifling engraving on back portion of bore riding slug.



    The base rifle was a BAM51 (serial no. UT0400059 just incase some lucky chap still has it) with a 533mm or 21in barrel. The barrel topped out at 43flbs and we switched to a 24in HW barrel and various internal mods to hit the 94flbs mark at 920fps with the 50gr FMG.

    The next notes in my workshop/ range book is in 2015 for slug weights and designs.

    [FONT=Helvetica]As some of you will be aware I have been working on making a .20cal slug that will work in standard choked barrels. I will still be sending testers to those people as the die is in its second version as the first showed some potential in the 22gr weight/ [/FONT][FONT=Helvetica]length[/FONT][FONT=Helvetica], however as with all "slug" type projectiles velocity is still key for spin stabilization and the first rifle tested pushed the 22gr only at . The velocity goals here will be 820 to 940+ or from 20flbs up. Low end slug mass from 13gr upto whatever individual rifles can handle for long range.[/FONT]

    [FONT=Helvetica]While the target below is no great group, it showed the potential of the 22gr slug, they are hitting [/FONT][FONT=Helvetica]straight[/FONT][FONT=Helvetica] and not key holing. The issue was velocity as on the test rifle was an HW100 and only pushed these at 696fps average probably about 200fps below ideal![/FONT]


    [FONT=Helvetica]The slugs will need to be tested in either a rifle [/FONT][FONT=Helvetica]producing[/FONT][FONT=Helvetica] 40flbs+ or as I have done I have changed the weight while keeping the ballistic profile the same. At 15.3 a 26flbs rifle should push these at 870fps.[/FONT]

    Expansion and rifling look good



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  2. #2
    MOT: Thomson Pneumatic Rifles

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    Default .22 slug development

    I have also then started 5.5mm slug development, also with the Boreriding principal.

    Start with tooling,

    Unhardened reamer


    Hardened Reamer;


    Hardened and Annealed;


    The results of the test die;


    The cutaway damages the skirt base, but shows the cavity. This is 21gr


    19gr and 21gr sectioned.


    Expansion testing at 57flbs




    Recovered slug;


    Lower energy shot to capture rifling on slug;


    Stay tuned.
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  3. #3
    MOT: Thomson Pneumatic Rifles

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    The first .22 die produces a .215cal slug of either 20 or 22 grains (these are standard hollow point slugs with a deep cup base and 3mm hollow point). These should be bore riding for rifles with tight chokes and require a rifle producing 36flbs of muzzle energy or higher (20gr 900fps or 850+ for 22gr). As the idea is to produce slugs that work in many barrels (like the original FMG slug) I would like to have them tested in as many rifle barrels as possible. If you have a rifle of this energy level and would like to test and also provide as much data as possible, please PM me.

    The next dies will produce .216; .217 and .218 sizes for now with special sizes on request.

    Stay tuned.
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  4. #4
    Sharp Shooter
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    Very interesting.
    Amazing work!
    I'll be following your progress...
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  5. #5
    MOT: Thomson Pneumatic Rifles

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    Thank you Sirshootalot.

    Depending on your set up your Jackal should like these.
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  6. #6
    Sharp Shooter
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    Quote Originally Posted by Warrick View Post
    Thank you Sirshootalot.

    Depending on your set up your Jackal should like these.
    I was thinking the same...I've just finished making a power adjuster, and I had it up to 60 ft.lbs recently...
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  7. #7
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    Quote Originally Posted by sirshootalot View Post
    I was thinking the same...I've just finished making a power adjuster, and I had it up to 60 ft.lbs recently...
    and I just made a 13gr, 7.35mm long slug for 20 to 26flbs! Will have to make you some 30 grainers for that beast!
    Last edited by Warrick; 28-01-20 at 15:09.
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  8. #8
    Sharp Shooter
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    Quote Originally Posted by Warrick View Post
    and I just made a 13gr, 7.35mm slug for 20 to 26flbs! Will have to make you some 30 grainers for that beast!
    Oh no!!

    At that power I only get a single figure shotcount!! LOL...!

    I've also sorted my P15's accuracy issues, and it's running at 30 ft.lbs.

    Even in the Jackal, I would prefer to stay below 50 ft.lbs...
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  9. #9
    Sharp Shooter

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    Quote Originally Posted by Warrick View Post
    The first .22 die produces a .215cal slug of either 20 or 22 grains (these are standard hollow point slugs with a deep cup base and 3mm hollow point). These should be bore riding for rifles with tight chokes and require a rifle producing 36flbs of muzzle energy or higher (20gr 900fps or 850+ for 22gr). As the idea is to produce slugs that work in many barrels (like the original FMG slug) I would like to have them tested in as many rifle barrels as possible. If you have a rifle of this energy level and would like to test and also provide as much data as possible, please PM me.

    The next dies will produce .216; .217 and .218 sizes for now with special sizes on request.

    Stay tuned.
    Fascinated by your work, as you seem to following this over a period of time, well done.
    I received two tins of H&N 21gr slugs on Friday (1 in .217 & 1 in .218) and have been playing with my Impact Mk1 and managed to achieve a setup that gives me 960fps and approx 40ft/lbs out of a 600mm STX Slug barrel.
    It will be interesting seeing the difference between these (with small HP) and your ones with a much larger HP, think yours might be longer, therefore more stable?
    Good luck in your endeavors.
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  10. #10
    MOT: Thomson Pneumatic Rifles

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    Quote Originally Posted by Jerkimiah View Post
    Fascinated by your work, as you seem to following this over a period of time, well done.
    I received two tins of H&N 21gr slugs on Friday (1 in .217 & 1 in .218) and have been playing with my Impact Mk1 and managed to achieve a setup that gives me 960fps and approx 40ft/lbs out of a 600mm STX Slug barrel.
    It will be interesting seeing the difference between these (with small HP) and your ones with a much larger HP, think yours might be longer, therefore more stable?
    Good luck in your endeavors.
    Hi Jeremiah,

    Thank you for your comments.

    Please let me know how your rifle performs with the H&N slugs and which caliber it seems to prefer .217 or .218. I bought a pack of each in the test packs for comparative testing as well.

    Yes the idea is too keep the BC with the length but get the velocity up for spin stabilization with lower power rifles (20+flbs). I will also be making them in heavier weights for 60flbs rifles.

    Thanks for reading

    - - - Updated - - -

    Quote Originally Posted by sirshootalot View Post
    Oh no!!

    At that power I only get a single figure shotcount!! LOL...!
    Well its a trade off , much like a V8 and an Uno
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  11. #11
    REP: WS Airguns

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    Great work done, Warrick!!!
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