Apr 202011

L to R = 9mm .40" .45" 5.7x28mm 5.56mm 7.62mm

I was doing some training recently with people who’ve ‘been there and done that’ and invariably the subject of the ‘best’ pistol round came up.  Usually these endless discussions revolve around .45 ACP vs .40 S&W with various other calibers added to confuse the discussion still further, but this time one of our group said he thought the 5.7x28mm round was the best.

I’d never really considered this round in the past because it isn’t a mainstream round – very few weapons out there fire it.  But I respected the guy who advocated it and so kept my silence and listened rather than spoke, and did some research subsequently.

I’ve got to tell you I’m hooked.  The 5.7×28 round has several significant advantages over all other pistol rounds – its speed and its dimensions, and to a lesser extent its weight.  It is reasonably priced, with its greatest weakness being lack of pistols that will accept this caliber.

Lethality Issues

Let’s consider speed first.  Most pistol rounds exit the muzzle at anywhere from somewhat below 900 feet per second up to about 1400 fps.  The speed of a bullet depends on its caliber, its weight, the powder load, and the barrel length.

To give some context :

Round Bullet (grains) MV (fps) ME (ft lbs)
.22 LR 37 LHP 975 78
.25 ACP 50 FMJ 760 64
.32 ACP 60 STHP 970 125
.380 ACP 90 JHP 1005 200
9×19 115 JHP 1175 341
9×19 +P 115 JHP 1300 425
.40 S&W 165 JHP 1150 485
.45 ACP 230 FMJ 839 360
.45 ACP +P 185 JHP 1140 530
5.7×28 40 V-Max 1750 320


Note – all measurements can vary +/- 10% depending on the cartridge manufacturer and barrel length.  In the case of the 5.7 round, speed is from an FN 5-7; add 200 fps if fired from a P90 and another 20 ft lbs; add an additional 150 fps (ie 350 fps total) if fired from a PS90.  (MV = Muzzle velocity; ME = Muzzle energy)

As for the round’s dimensions, it has a smaller diameter than any of the other bullets except for the .22 round.  5.7mm is .224″ – a single thousandth of an inch larger in diameter than a 5.56mm/.223″ rifle round.  A narrow diameter for any round is not normally considered a good thing – in simplistic terms, the larger the diameter, the larger the wound cavity created.

(But, on the other hand, does it really make that much difference whether the wound cavity is created by a bullet measuring 0.4″ in diameter or one measuring 0.45″ in diameter?  Both are tiny compared to the size of a person’s torso.)

The notable thing about this round is that it is narrow but long – it measures 21.6mm (0.85″) in length (the 28mm measurement relates to the length of the cartridge case, not to the length of the bullet).  In round figures, it is almost four times longer than its diameter.  This compares to standard 9mm rounds which are about 1.5 times as long as they are wide, sometimes less.

The 5.7×28 round also has its center of mass further back towards the rear of the bullet than is the case with most other pistol bullets, due to its long gracefully pointing nose.

Accordingly, when a 5.7×28 round hits a target, the bullet tends to tumble (the same as the .223 round).  This does two things.  It makes for a much larger wound cavity than it would if drilling a tidy hole as would otherwise be the case, and it ensures that all the bullet’s energy is transferred to the target, with less danger of the bullet zipping out the back side of the target and on to whatever other things are behind it.

Now let’s return to the bullet’s speed to consider another measure of bullet lethality.  As a disclaimer up front, I should acknowledge that all studies of all types of bullet lethality can be considered as incomplete and inconclusive, and as such there are no exact factors to optimize in designing the ultimate self-defense round.  That is why there is so much (and such repetitive) discussion over the relative effective stopping power of different bullets.

Hydrostatic Shock

With that disclaimer out of the way, the phenomenon of hydrostatic shock is a somewhat controversial factor which some authorities believe to be a significant contributor to a bullet’s ability to rapidly incapacitate an aggressor (ie faster than the time it takes for the aggressor to simply bleed out).  Some proponents of hydrostatic shock even claim that a bullet hit in the torso will transfer energy through the body’s non-compressible fluids to the brain.

Hydrostatic shock effects are not only somewhat controversial, but also somewhat secondary for most pistol rounds, because the pistol rounds do not travel fast enough to have an appreciable hydrostatic shock effect.  The FBI recommends that pistol rounds be chosen primarily on the basis of their ability to penetrate 12″ of ballistic gelatin.

However, the 5.7x28mm round is considered to provide a greater hydrostatic shock effect than most other pistol calibers and bullets (and seems to penetrate about 12″ into ballistic gelatin as well).

Those who argue against hydrostatic shock say that accurate bullet placement into vital organs and areas of the body is the most certain approach to ensuring capacitation.  A possible response to that statement is to accept it, but to point out that few of us can guarantee such accuracy under stress in a volatile situation, and so any added factors that can help us win the fight are to be embraced enthusiastically.  It would seem the 5.7 round offers the best of both worlds – sufficient penetrative ability to be reasonably likely to reach vital organs if hitting the target in an optimum zone, and the added bonus of hydrostatic shock, ‘whether it is needed or not’.

This has certainly been accepted by Navy Seals, Secret Service, and the Federal Protective Service, all of whom have chosen 5.7mm rounds and weapons for their operatives.

The 5.7 round is rated as having an effective range of 55 yards when fired from a FN Five-seveN pistol, or 220 yards when fired from a P90.

The very high velocity of the round also gives it a very flat trajectory, and allows for optimum accuracy.

Recoil & Flash

The 5.7x28mm round gives you something for nothing – it leaves the gun with a goodly amount of energy, in high speed search of something to transfer its energy into for maximum effect, but does so without the expected amount of recoil.

The recoil experienced when firing a 5.7×28 round through a FN Five-seveN pistol is appreciably less than the recoil experienced firing a 9mm round through a Glock 17.  This is all the more surprising because the Glock is a slightly heavier weapon (both weigh about 22 oz unloaded but 17 rounds of 9mm ammo in a Glock magazine weigh considerably more than 20 rounds of 5.7mm in a FN magazine).  It has been cited as having 30% less recoil than a regular 9mm round.

Although recoil is low, muzzle blast and flash is appreciably higher – I’ve not fired the cartridge at night, but based on the visible flash from daytime shooting, I’d imagine it to have appreciable impact on your night vision acuity if you had to use it in a dark environment.


The cartridges weigh about half the weight of typical 9mm cartridges.  This, plus their small size, makes it very convenient to carry plenty of spare ammunition.


Regular civilian grade ammunition can be purchased at around $20 per 50 round box of the SS197SR cartridges and $25 per 50 round box of the SS195LF cartridges.  This makes it priced closely comparable to regular grade .45 ACP and only a little more than .40 S&W ammo.  The same source sells standard 9mm ammo for around $12/50 rounds.

When you keep in mind you don’t need to buy outrageously expensive self defense rounds in addition to the ammo you buy for practice and plinking, it seems clear that from an affordability point of view, the 5.7 round is no worse than most other standard caliber rounds.


The anti-gun nuts – and I use the word ‘nuts’ advisedly because they seldom allow common sense to interfere with their hysterical dislike of anything that goes ‘bang’ have denounced the 5.7×28 round as being a ‘cop killer’ round with alleged magic properties to penetrate through bullet proof vests.

These are probably the same people who described the Glock 17 pistol, for the first few years after its introduction, as a ‘plastic gun’ which they claimed would be undetectable when going through airport security, due to ‘having no metal’ in it.  Of course, this is an utterly nonsensical statement – the entire barrel, slide, and assorted other pieces of the action are all made of good solid steel, and with airport metal detectors capable of detecting a single penny in your pocket, they’d never have any problem with over a pound of solid steel in the so-called ‘plastic’ gun.

The claims about the 5.7×28 round are similarly specious.  It is true that one of the original development goals was to create a bullet with better penetrating power to get through battlefield flak jackets, and for sure, an armor-piercing version of the round is available, although only to the military and law enforcement, and this round is definitely capable of penetrating some kevlar vests.

But most pistol and rifle rounds are offered in armor-piercing variations, so the fact there’s an a/p version of the 5.7×28 round is not unusual.

Most importantly, however, civilians can only buy two versions of the 5.7×28 round – the SS195LF (lead free) and the SS197SR (sporting round).  Neither are armor-piercing.  Only the SS190 is classified by ATF as AP and sale is restricted to law enforcement and military only.

Unfortunately it isn’t only the rabid anti-gunners who ascribe magical powers to this round.  At the local gun range, the generally knowledgeable range master claimed that the 5.7×28 round traveled at 3300 fps (almost exactly twice the actual speed of 1750 fps) and could penetrate ‘both sides of a kevlar helmet’.

Here’s an interesting critique of the round which compares it to some high powered .22 cartridges, and as this comparison would indicate, it is absolutely not a cop-killer with any magical penetration powers at all.  Unstated in the article is the fact that these bullets (like 5.56mm/.223″ rifle rounds) tend to tumble when striking a target – this is a great way to transfer the bullet’s energy to the target, to create a wider wound channel, and to avoid over-penetration, but it is absolutely useless in terms of penetrating a bullet proof vest (or much else for that matter, either).

Why Is the 5.7×28 Round Not More Popular?

So, if you’ve read all this way, you’ll be seeing this as an excellent round with a lots of pluses and no minuses.  Why hasn’t there been a rush to adopt it by handgun manufacturers and military/law enforcement institutions?  In contrast, the .40 S&W, first introduced in 1990, has quickly won widespread acclaim and adoption, whereas the 5.7mm round languishes with little marketplace awareness and even less acceptance.

It is hard to have an answer to this relevant question.  My own best guess is that most shooters are hung up on the size issue.  A bigger bullet is intuitively better than a smaller bullet, and when you think back to the introduction of the .40 S&W round, it was not so much displacing/replacing the even larger .45 ACP round as it was substituting for smaller rounds such as 9mm.  The ‘bigger is better’ crowd were able to welcome the .40 S&W without having to change their paradigm.

On the other hand, the 5.7mm round is tiny.  It is long and narrow and ‘delicate’ in appearance.  It weighs only 40 grains, compared to 115 or more for a 9mm round, 155 or more for a .40 S&W and as much as 230 grains for a .45 ACP round.

This makes it difficult to accept the 5.7mm round as being better than the larger heavier rounds it competes with.  Add to that the successful scare-mongering and hate-mongering by the anti-gun forces so as to make it a controversial round that politically correct shooters may choose to avoid, and this excellent round has found little acceptance.

Another reason is the difficulty in adapting existing designs of pistols to chamber the 5.7mm round.  It is, for example, relatively simple to convert a pistol between 9mm and .40 S&W (look at the Glock family for an obvious example).  But due to the relatively long length of the 5.7mm round, it needs major alterations to the design of the grip (to hold the much longer magazine) and to the slide and receiver (allowing the slide to go back much further to eject spent cases and feed new rounds into the chamber.  It is fair to say that the 5.7x28mm cartridge is pushing the outer limits of cartridge dimensions that can be used in an ergonomic pistol design.

Lastly, the chicken and egg effect is definitely in play.  If you want to use the 5.7mm round, you have effectively only one handgun choice – the FN Herstal Five-seveN; an ugly, expensive and bulky weapon with nothing to recommend it other than being chambered for the 5.7mm round.  This further discourages shooters from seeking out 5.7mm based pistols, which discourages the pistol manufacturers from developing new pistols.


The 5.7x28mm round is an impressive round in every respect, and offers greater stopping power combined with greater controllability (as compared to most other mainstream pistol rounds), all in a tiny sized package, and at an affordable cost per round.

With so much going for it, and very little if any downside, it deserves a more prominent role in our awareness than it currently has.

  23 Responses to “5.7x28mm Ammo Review”

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  1. […] There have also been new calibers (most notably the .40 S&W, introduced in 1990, and the 5.7×28, introduced in 1993) but these are outside the scope of this […]

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