Looking for legitimate info on 5.7x28 ballistics.

[ClickClickD'oh]

For pistol use, 9x19 has the same muzzle energy in a standard load but when you look at the +P and +P+ offerings and all of the different pistol configurations, it makes it difficult for me to see why you would want to carry 5.7 in a pistol.

Because muzzle energy isn't the be all end all of wounding.

For a rifle or carbine, 5.56 is a little bit harder to control but the energy advantages far outweigh the disadvantages.

Same could be said of the AR-15 with this:

"For a rifle or carbine, 7.62 is a little bit harder to control but the energy advantages far outweigh the disadvantages."

 

[Trent]

Same could be said of the AR-15 with this:

"For a rifle or carbine, 7.62 is a little bit harder to control but the energy advantages far outweigh the disadvantages."

Or 50 BMG.

 

[Orion8472]

Hmmmmmm. . . . well, thanks again for the input, guys.

 

[barnbwt]

"For pistol use, 9x19 has the same muzzle energy in a standard load but when you look at the +P and +P+ offerings and all of the different pistol configurations, it makes it difficult for me to see why you would want to carry 5.7 in a pistol."
Because a five-seven fully loaded weighs less than a G17 with no magazine. I'd call that an advantage, especially considering the 5.7 gives up little or nothing over "acceptable" 9mm loads that were widely used/praised for years until +P/+P+ marketing allowed Bigger Gun Syndrome to push the bar a few ticks higher. The advantage is even more pronounced for the P90, which I'd wager weighs less than many PCCs or ARs, while carrying 50 rounds at one time. 9mm and 223 are great, but they are bigger rounds that make for heavier magazines. If a smaller round can deliver sufficiently, why go bigger?

Not enough backpackers write gun articles, nor enough shooters read Henry David Thoreau, I suppose

TCB

 

[481]

Because a five-seven fully loaded weighs less than a G17 with no magazine. I'd call that an advantage, especially considering the 5.7 gives up little or nothing over "acceptable" 9mm loads that were widely used/praised for years until +P/+P+ marketing allowed Bigger Gun Syndrome to push the bar a few ticks higher.

A lighter pistol doesn't equate to much of an advantage against a lethal threat. It's what the round hits that matters most.

 

[Trent]

A lighter pistol doesn't equate to much of an advantage against a lethal threat. It's what the round hits that matters most.

Or doesn't hit. I'd rather not hit my kid on an over penetration.

Remember I keep a 5.7 handy in main level of the house because of children and other things I care about, which (may or may not, no way to tell) be behind the bad guy or wall next to him. If 5 bad guys kick in my door RIGHT NOW (remember 5 armed guys went in to my neighbors house one night not so long ago), I can't stop and yell "TIME OUT, I need to know that none of my 5 kids are in my line of fire behind you, or that wall next to you..."

The closest thing for me would be a 380 ACP; it would fit my needs, for about the same reason (~9-10" penetration on meat, and poor barrier penetration), but I can't find a 380 with a 20 round capacity.

At night I keep a 9x19 handy (CZ75), because my kids are all tucked away at night and I know there's a hard barrier between me and them (carefully placed bookshelves / dressers, in addition to the walls.)

Different guns for different rooms.

My outside the home carry choice is very different from either one of them.

 

[eldon519]

There are quite a few agencies using that too. I wouldn't exactly call the Texas DPS and USSS grassroots.

I think you misunderstood what I am saying. I'm not saying there aren't end users of both; I'm saying that the supposed advantage of either caliber is grassroots. Looking at the Federal HST and Winchester Ranger T and Ranger bonded rounds, the .357 SIG performs nearly identical to 9mm through a variety of barriers on these companies' own promotional information. Likewise expert opinions and actual experimental data don't show the 5.7x28 to be the lightning bolt of Zeus its internet proponents would have you believe. Neither has been a raging commercial or LEO/military success. Given that this thread is about the 5.7x28 specifically out of a handgun and not a P90, isn't it telling that the USSS does not use the Five-Seven as their standard issue pistol? Rumor has it the Texas DPS is going from 357 SIG to 9mm too.

 

[barnbwt]

Yup, the DPS is going with the M&P over the SIG offering, due almost entirely to cost. As far as agencies adopting the 5.7x28, keep in mind that there are just as many skeptics, haters, and biased fence-sitters in those board rooms as on the web, and that such a divergent platform has its own "retooling" costs should they adopt a gun with a totally different manual of arms and maintenance considerations. Keep in mind that the military did extensive terminal testing on the 276Pedersen cartridge, proved it equally lethal as 30-06, yet still insisted it wasn't suitable for combat

It's also been quite a while since anyone claimed the 5.7x28 was a "lightning bolt of Zeus" and anyone who did in the first place was speaking from the same ignorance as people who say it's a glorified 22magnum. When people exclaim how effective it is, it is because they are surprised how damaging it is for a round its size, when 'horse sense' says it should reach only like half what 9mm achieves, as opposed to roughly the same result.

The fanboy who says the 5.7 matches or exceeds the 45ACP or 5.56 is an utter myth.

TCB

 

[ClickClickD'oh]

Rumor has it the Texas DPS is going from 357 SIG to 9mm too.

Rumor, hell. The January academy class will be issued S&W M&P9s instead of the Sigs. It was a cost cutting measure (pistols and ammo both cheaper) by the new administration. Not a popular one amongst the troopers.

 

[Trent]

When people exclaim how effective it is, it is because they are surprised how damaging it is for a round its size, when 'horse sense' says it should reach only like half what 9mm achieves, as opposed to roughly the same result.

TCB

Barn; much of that "huh?" value when seeing what the round does to flesh is due to pushing a tiny, pointed, frangible projectile at extremely fast speeds. On paper the kinetic energy is only in the lower 300ft/lb, which the 9mm utterly destroys.

The 9mm will absolutely penetrate deeper; no doubt about it, as it has mass on it's side. It'll punch through bone and other obstructions better. It creates a neat, round permanent crush cavity until it slows down enough just to push tissue aside, then it stops.

But what a 40gr projectile fired out of a 5.7x28 does in the first 4-6" of it's penetration is put quite simply, very nasty stuff. After 4-6", one the jacket fragments (or sheds), the core just drills through until it stops, leaving a tiny wound track that doesn't do much damage.

A friend of mine once brought over a VHS tape (which dates both of us, unfortunately), called "Exploding Varmints". It was an hour+ long frag fest of prairie dog hunting, mostly high velocity lightweight varmint rounds being used to spectacular terminal effect on rodent pests in the upper great plains. (Many shots were replayed in ultra slow motion..)

Somewhere in that gory hunting movie, is a lesson to learn about high velocity lightweight rounds that fragment on impact. They are incredibly damaging to soft tissue.

Which brings me back to the point I made earlier; two basic ways to stop an aggressor with projectile weapons. CNS shutdown (which any bullet can do equally well, if it hits the brain stem, upper spine, etc), or blood loss and unconsciousness.

Massive soft tissue disruption lends itself very well to the blood loss and unconsciousness end of that equation. The thought of taking a high velocity 40 gr .224" projectile anywhere near the heart arterial cluster, or liver is just.. well, I hope it never happens.

 

[eldon519]

You've basically described a Glaser Safety Slug. I'm sure they would blow up a prairie dog too.

 

[Trent]

Yeah the wounding patterns about 4" in are strikingly similar, Eldon.

 

[browningguy]

Originally Posted by Orion8472 
That's a rather scathing report on the round, I'd say. 

No it isn't. It's just sensational quotes. For example:

I agree, the good doctor's report isn't a worthwhile report. It's a sensationalist diatribe by 3-4 guys that don't like the 5.7 (or the smaller HK round) with zero backup, show me the cases where they had to spray 20 rounds into a perp on full auto to put him down.

Testing on gel and pork shoulders is much more worthwhile to me. I don't use a 5.7 for SD but do shoot an AR57 upper quite a bit and have been very happy with it on varmints etc. If it fit's your hand and you shoot it well I wouldn't have any problem with someone using it.

 

[barnbwt]

Yeah, the rep about the round needing 10 hits to do anything stems from there being absolutely no reason not to fire additional rounds in each burst since the recoil is so minimal, the magazine so big, and the rate of fire in the P90 so high.

"Somewhere in that gory hunting movie, is a lesson to learn about high velocity lightweight rounds that fragment on impact. They are incredibly damaging to soft tissue."
I think this is where the 'legitimate' debate about the 5.7's effectiveness vs. potential comes in. People get all distracted by stuff like temporary/permanent wound cavities and whatnot, when what is actually happening is that the interaction of a projectile vs. tissue changes abruptly past a certain point, commonly associated with rifle calibers. Just like how lead only acts more and more penetrative until you get to the speed it deforms, expanding projectiles act more and more like a pebble hitting water until they fail completely. The 5.7 is borderline at the point where that "splash" effect happens with regards to the wound cavity, but is also beyond the failure point of the bullet so it shatters, and that is what makes it a bit different from, say, a 30-06 FMJ going the same speed.

The debate, I think, about 5.7, is how much a difference the splashing aspect plays in vs. the fragementation in causing damage, and how much even a modest increase in speed/power would amplify the first behavior to make a much more damaging round without giving up much size or recoil. Lotta people think it should have been tricked out just a bit more, to act more truly rifle-like. They may have a point that more speed would achieve that, but I personally think they are overlooking that the round didn't need that extra margin to do its job and that the primary goal of being small and easier to control was worth retaining. I think it would be interesting to see a 5.7 or ballistic twin loaded up with solid bronze slugs in these gel tests, since would give a clearer picture of what the shear velocity accomplishes vs. the bullet construction (or de-construction, to be more accurate)

TCB

 

[Trent]

Well I can testify to the "fragment on impact" even hitting something as soft as plastic. Today I shot my chronograph with the PS90 doing load development. You can read about it here in the reloading forum.

The bullet fragmented after deflecting off thin plastic at a shallow angle. Made a real mess of my chronograph.

I don't know what velocity it was travelling since my chronograph just said "ERR" on the LCD screen after it was hit.

Based on the load volume and past load data that I did chronograph I can postulate "slightly above 2300fps".

http://www.thehighroad.org/showpost.php?p=9280617&postcount=47

If you see how much fragmentation it did just hitting PLASTIC .. it seals the debate about why I choose this for home defense with a wife, 5 children, 3 dogs, and 4 cats running around the house.

The 40 grain Hornaday V-Max jackets are so incredibly thin they won't make it to the 50 yard line if pushed at a high velocity. I've shot them out of my 22-250 at approx 3,800 fps and they don't ever reach the target. About 20-30 yards out there's just a gray "poof" as the round disintegrates in flight.

I wouldn't advise loading solid bronze projectiles; they're still on the ATF prohibited list as armor piercing.

See more here; and note that Barnes is not even TRYING to get the .223 projectile de-listed because there are so many AR pistols and 5.7x28 platforms out there.

http://www.barnesbullets.com/wp-con...Barnes-Customer-Update-Banded-Solids-2012.pdf

 

[Trent]

Barnbwt; thought of an interesting side experiment to do though.

2 layers of drywall with a pork shoulder or beef roast a few inches behind it. See what would happen firing through a wall and hitting meat on the other side. Then try again with a 2x4 in between the drywall layers to see what happens if it hits a single stud.

I really need to confirm that these come apart just by hitting drywall.

 

[barnbwt]

From the pistol, I've sent the 5.7 go through a total of four spaced-apart layers of 3/8" drywall and it only punched a hole through them. Round was SS197 (I don't recall "SR" being on the box but I think they're the same). I posit that the velocity was pretty minimal by the last sheet and even after the third, but it doesn't look like the short barrel gets the rounds quite fast enough to blow up after only a single layer or so. I fully believe the round would be potentially fatal to someone on the far side of a single wood-frame interior wall regardless of the platform, but gel tests suggest rounds from the carbine would stop sooner (much sooner, depending on the type of surface they first hit). As dense as sheetrock is, it logically follows that the round can't be retaining much juice as it passes through that mass, but obviously there remains enough to at least punch through (then again, so can a pellet gun, but those are rarely lethal to bystanders)

Like I said, I think the round's velocity is on the threshold of behaving more like a rifle round, but the pistol sits a bit below that, and therefore the performance is markedly different from the carbine. When your chrono is up again, checking velocity through barriers and into the pork may be an interesting test, since the bullet will have deformed at least a bunch in addition to slowing down. Have you ever looked into the 22TCM? Supposedly goes a bit faster than 5.7, so it probably fragments more out of the 9mm-sized pistols chambered for it (the RIA 1911 variant, for example). If STI came out with one I'd probably go for it

Part of me wonders if the bullet may hold together better through sheetrock than we expect because that material is brittle rather than a liquid, and can be "sheared through" much more efficiently by a fast object than a fluid can be. The same principle the aluminum core penetrator works on. In that case, the sheetrock may slow the bullet below the fragmentation threshold but not break it apart, resulting in a more traditional terminal performance on the far side. That would explain the four circular .22" holes (becoming more ragged and tearing out more gypsum by the fourth panel) but catastrophic failure upon meat-slap. I need to find another place around here that will let me run more "experiments". I only did a handful of shots, from nearly point-blank range, and hardly scientific. I've wondered, for instance, how the sporting rounds do against stuff like glass or porcelain; whether they punch through or splatter a shotgun-blast of shrapnel through to the far side.

Thanks for the terminal ballistic data on chronographs

TCB

 

[Trent]

You're welcome.

At least the ProChrono makers will fix it regardless of condition for a max cost of 1/2 retail.

Hope I don't have to use that too frequently. I *completely* forgot that the PS90 line of bore / line of sight is significantly higher than my other rifles.

 

[Trent]

Also; I believe the jacket comes apart from rapid deceleration. It's so thin that it can't resist the lead "busting out". So if drywall doesn't offer enough resistance, it won't shed the jacket and the round will stay intact. As velocity or density increases it changes that equation.

It DOES happen fast though - and as soon as it does you have little tiny sharp copper jacket pieces going mach 2 in all directions.

When it strikes water or plywood, it pretty much vaporizes the round. Drywall is pretty soft stuff though.

 

[Trent]

One other thing, between the 5.7 pistol, 5.7 rifle, 223 rifle, and 22-250 I could test the 40 grain V-Max bullet through a BIG velocity range against different media.

Hmm. I see a summer project coming on.

 

[barnbwt]

I think 22-250 might be a tad much in a pistol, though

I do think there is a dearth of destructive-bullet testing out there; seems like we have a fairly good read on how hollow point and other expanders work, and a very good understanding of how low-velocity hard cast works. But the deconstruction adds a whole new set of variables that have yet to be explored. Are big pieces better than small one? Does whether the bullet shatters immediately vs. breaking into progressively smaller pieces matter (secondary fragmentation)? Do the broken pieces form their own temporary/permanent cavities, or do they act like a cloud of hardcast/buckshot? Does the odd shape of the pieces cause their path to wander like tumbling rounds? Do certain fragment shapes spray outward more quickly from the point of impact than others? I think the potential is there for essentially a composite bullet with a penetrating core and a jacket and designed to break away into specific shapes which cause widespread but shallower damage, whose design variables can be modified to achieve both of those extremes as well (i.e. a bronze 5.7 round would probably be a hell of a penetrator, but a Vmax jacket filled with Tungsten sinter would probably never go through a leg let alone a wall but would cause irreparable damage to whatever it hits first.) Yeah, I know the ATF laws make such development off limits, but the question is still validly explored in rifles like 22-250

A chart with what I've learned about terminal ballistics so far:
Slow

-Hardcast goes deeper the faster or heavier it is so long as no deformation occurs
-Expanding bullet goes deeper and makes a much wider cavity the faster it is, so long as it does not shed lead or jacket. Weight affects depth only.
-Splattering bullet goes deeper (probably) the heavier it is, and has a wider/denser "cone of destruction" the faster or more fragile it is (probably)
-Projectile's kinetic energy is dissipated as thermal energy upon impact, burning a hole through the target with a ball of superheated plasma

Fast

TCB

 

[Orion8472]

Has anyone done a "pork rib in front of ballistic gel" type of test to emmulate effectiveness in a defensive situation?

Please continue the normal "through drywall" conversation, but for me, I don't plan on using the SS197SR/Five Seven setup for home defense. More for a [SHTF] sitation that I hope never EVER happens anyway.

 

[Trent]

Orion - I haven't seen one off-hand but that's an interesting one. If you are shooting center mass, ribs definitely come in to play, and are hard enough to cause the bullet to fragment immediately.

I've got a friend who wants to play with ballistic gel this spring; when the winter is over we might mess around some with it.

 

[Orion8472]

Trent, as I see it, this debate may never be solved until such a test is done. I may hit up a couple of people on youtube to see if they will do one.

 

[481]

Originally Posted by Orion8472 
That's a rather scathing report on the round, I'd say. 

No it isn't. It's just sensational quotes. For example:

I agree, the good doctor's report isn't a worthwhile report. It's a sensationalist diatribe by 3-4 guys that don't like the 5.7 (or the smaller HK round) with zero backup, show me the cases where they had to spray 20 rounds into a perp on full auto to put him down.

Testing on gel and pork shoulders is much more worthwhile to me. I don't use a 5.7 for SD but do shoot an AR57 upper quite a bit and have been very happy with it on varmints etc. If it fit's your hand and you shoot it well I wouldn't have any problem with someone using it.

I'd not be so quick to discard the report out of hand.

Actually, Dr. Roberts' report-

http://pistol-forum.com/showthread.php?4338-Small-Caliber-PDW-s-FN-5-7-mm-HK-4-6-mm

-is a condensed description of the experiences and findings of several LE agencies and professional firearms trainers -it is not just 3-4 random guys complaining about the round. There is obviously quite a bit more behind the content of the link as I doubt very much that Dr. Roberts simply pulled it out of thin air.