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