Estimated reading time: 2 minutes
Last week on DemolitionRanch, Matt experimented with an ultra-high-velocity round that combines a .17 caliber bullet with a 5.56 case, resulting in a wildcat cartridge known as the 17-556.
Created by KAK Industry, this cartridge takes a tiny, lightweight 17-caliber bullet and pairs it with the power of a 5.56 casing, leading to extremely high speeds that Matt was excited to test.
The 17-556 cartridge moves much, much faster than standard rounds. Compared to a regular .17 HMR, which travels at around 2,500 feet per second (fps), the 17-556 can hit speeds of over 5,000 fps.
For reference, typical high-power rounds like .375 CheyTac or .50 BMG max out around 3,000-3,500 fps.
“It’s almost a mile per second at the muzzle,” Matt observed, pointing out the extreme velocity.
To showcase the speed difference, Matt tested both the .17 HMR and 5.56 rounds on various targets, including watermelons, ballistic gel, and bottles of Fanta.
The results were striking: the .17 HMR would puncture targets, but the 17-556 would cause dramatic explosions, showing the power increase from its incredible speed.
As Matt noted, “Exact same bullet passing through the exact same watermelon going twice as fast just made that difference. That’s insane.”
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The high-velocity rounds also performed well against different types of body armor. While the 17-556 couldn’t penetrate level IV armor, it went clean through level IIIA.
In ballistic gel testing, both the .17 HMR and 17-556 reached similar penetration depths, though the wildcat round created a larger wound cavity due to its higher speed.
In a final experiment, Matt tested different custom loads from CAC to see just how fast he could push the cartridge. Using 12.5-grain brass bullets, the 17-556 reached an impressive 5,220 fps, setting a new speed record for the channel.
The final test hit a simulated skull target, proving that even the smallest, lightest bullets could deliver substantial damage at these speeds.
With the 17-556, DemolitionRanch demonstrated the intense effects of speed and energy on small-caliber rounds.
As Matt concluded, this wildcat cartridge brings a unique approach to high-velocity shooting, showing just how much power can come from a tiny bullet when it’s moving at extreme speeds.
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Nice to see you’ve reinvented the wheel.
I’ve been using my old Lyman mold for the 145gr. Keith HP for years now.
Together with my Combat Master Piece in 38Spl. we have fed many a jackrabbit to the coyotes.