.22 Mag vs. 5.7x28mm

After reading through this article at The Firearm Blog, I’d now like someone to do actual side by side ballistic testing of 5.7x28mm ammo vs .22 Magnum ammo.  Both from pistol length barrels and carbine length barrels.

Off the top of my head, the best platform for this would be one of the T/C Encore or Contender guns.  Because they’re modular, all you’d need to do would be to get a 16 inch .22 Magnum barrel, a 16 inch 5.7x28mm barrel for the rifle length test, and then get a set of 5 inch barrels in both calibers for the pistol test.  This way you can eliminate barrel length as a variable in terminal performance.

As much as I love the .22 Magnum, it’s not (despite what the internet told you) the same ballistically as the 5.7 round.  The round fired from the Five-seveN is a much more aerodynamic bullet, as well as using powder optimized for pistol use.  Of course, this is probably one of those things that I’ll never actually get the chance to test, which is really too bad – I think I’d be an interesting side by side comparison.


  1. Still the .22 mag gun is cheaper, the ammo is cheaper, and when comparing say the PMR-30 holds 10 more pills in the flush-fit box to the FiveSeveN’s 20.

    So it doesn’t matter who generates more muzzle energy (*hint .45 ACP!*)

    Oh and the FiveSeveN has a mag disconnect!

  2. then get a set of 5 inch barrels in both calibers for the pistol test.

    …and an NFA stamp or separate lower. Stupid, stupid law.

    Either that, or a sympathetic foreigner from one of those countries where the government trusts people with single-shot weapons.

  3. “The round fired from the Five-seveN is a much more aerodynamic bullet, as well as using powder optimized for pistol use.”

    Are you sure about the powder being optimized for pistol use? My understanding is that the round was designed for use in the P90 rifle, and the Five-seveN was then designed around the cartridge to allow one type of ammunition to be used for both the primary weapon and sidearm – simplifying logistics. Using pistol powder in a round designed primarily for a rifle would seem counterproductive.

  4. Jake the P90 in its military configuration was meant for a 10″ PDW/SMG.

    Maybe I’m splitting hairs but calling that a “Rifle” seems a bit generous. But of course 10″ is a hair long for pistols, it certainly won’t suffer as much of a detriment that happens when people shoot .223 out of pistols.

  5. Weer’d: I’m not really familiar with the P90, so I didn’t realize it was such a short barrel. Thanks.

    I would still think the round would be optimized for the rifle rather than the pistol, though. It makes more sense to accept the decrease in performance in the sidearm, rather than the primary weapon, and trying to balance performance between the two would be even worse, since you’d probably end up with suboptimal performance from both.

  6. That reply as “riposte3” was me posting from my phone, BTW. I didn’t realize it used a different name until just now.

  7. At normal pistol distances the more aerodynamic bullet won’t make a noticable difference in impact velocity. It will, of course, affect the terminal performance. But unless the 5.7 bullet is designed to expand rather than be “armor piercing” the .22 Mag is probably going to have the edge on wounding potential.

    1. Frank, I’d like to try it. It might be a fun “winter time project” when I’m not busy destroying a Ruger LCR.

      Joe, I was thinking that the 5.7 bullet would retain velocity better over longer ranges because it’s more aerodynamic.

  8. I think you might be on to something if you use 10% ballistic gelatin in your testing. Comparing penetration depths and cavity sizes might actually point out some differences……..er, or they might be differences of extremely small degrees.

    All The Best,
    Frank W. James

  9. Apples and Oranges.

    The poweder in a 22WMR is a bit slower burning and has less puresure than the 5.7. Its just a fact.

    Now, in a rifle length (16″), then the come out almost equal. Maybe 100fps towards the 5.7, but, they use almost the exact same bullet.

    I know this first hand as that hornady and cci/speer both make bullets for the 22WMR and 5.7.

    Its the case, powder, and primer that are different. Which changes the pressure and burn rate.

    Yes, I plan to get a PMR-30, as I have been waiting on getting a 22WMR pistol for quite some time and like the quality/service from Kel-Tec.

  10. I went to the Brass Fetcher website and presuming I interpreted everything correctly, I am underwhelmed by the 5.7 compared to the 22 Mag, using the same weight bullet, the 5.7 gained about 150 fps, although the 40gr 5.7 load had a significant standard deviation for the 3 shots in the test.

    On an under related note, why is it that .22 Magnum revolvers, regardless of manufacture, seems to need the cylinders brushed out within 20 rounds?

  11. FYI, a buddy of mine who has a P90 attempted to handload for it. He found that after a few loadings he was having severe FTE issues.

    Seems that 5.7x28mm is more-or-less a straight-sided case with almost no taper, and there is some sort of low-friction coating on the cases to allow extraction. After a few loadings, and tumblings , this coating is rubbed off and the cases stick.

    So both 5.7×28, and .22 WMR can both be essentially considered non-re-loadable.

  12. Michael – the reason is that the slow burning rifle powder in the .22 Magnum case tends to well, not burn and then deposit crud everywhere.

  13. Caleb,

    At 50 yards the 5.7 is going to lose something on the order of 140 fps. The .22 Magnum is going to lose about 165 fps. And that is for 50 yards–far more than most pistol shootings take place at.

    In terms of terminal performance the velocity is probably not going to be the determining factor. Almost for certain it’s going to be bullet design.

    If the 5.7 is an armor pierce bullet but doesn’t encounter any armor (as was almost for certain the case in the Ft hood casualties) then my bet (and I don’t bet unless I’m pretty certain I’m going to win) is that .22 Mag is going to have better terminal performance.

    Since it is unlikely the ammo used at Ft. Hood was AP we can’t really say with a great deal of certainty which cartridge would have been “more deadly” until we know the type of bullet actually used.

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