For the sake of argument, 5.7x28 vs 5.56x45 for standard issue round

[MTMilitiaman]

And many of us will never understand why people try to make the 5.56 into something it isn't.

It's a great varmint round. It works well on coyotes. But if the military can rate it as a combat round out to 500 yards and put 800 round BDC on our optics, then the 5.7 really is a comparatively 200 yard round.

Expecting what the military does from the 5.56mm isn't much more of a stretch than expecting the 5.7 to perform in modern sub-100 meter urban combat. Even the 9x19mm MP5 was rated for 80 yards. That's 20 yards more than the reported average engagement distance in Iraq...

 

[Eric F]

MTMilitiaman the 5.56 was designed to be a 500m combat round. that is what it was built for.

FN when the 5.7 was new made it plain in many articles that it is a close in armor defeating round.

 

[Tomac]

I'm a big fan of the 5.7 for HD/SD use but even I wouldn't suggest it for front-line std issue use. To correct an earlier poster, 5.7 ammo weighs half as much as 5.56 ammo, a fully loaded P90/PS90 50rd mag weighs about the same as a fully loaded 5.56 30rd mag.
Tomac

 

[fearless leader]

I agree with DEER HUNTER.
The 7.62x25mm Tokarev has it all over the FN round in performance.

I wonder how it stacks up to the 30 carbine?

It doesn't matter. Barack Obama will probably outfit our military with paintball guns.

 

[MTMilitiaman]

MTMilitiaman the 5.56 was designed to be a 500m combat round. that is what it was built for.

Perhaps. But how well it fills that role is debatable. I feel that is more than just a little optimistic.

The military could design a car around a 4-cylinder engine and call it a drag racer, but that doesn't mean it is particularly well suited to the task, despite the designer's intentions...

 

[Evil Monkey]

That's 20 yards more than the reported average engagement distance in Iraq...

Are you trying to say that since the reality in one theater of warfare tends to support your theory of a 5.7mm infantry weapon, that suddenly it should be accepted? Non sense. And what about other methods of warfare? Environments a soldier will fight through? The 5.7mm would never come close to achieving the versatility the 5.56x45mm, 5.45x39mm, 7.62x39mm, 5.8x42mm, 6.5x39mm, and 6.8x43mm.

And even if a 5.7mm, 100rd capacity, 1,000rpm weapon was to be adopted as general issue, the squad would STILL require a base of fire MG. There must be something that will pepper long range targets with authority and have the capability to chew through hard targets. If you still need a MG in the squad, then it looks like the full auto 5.7mm doctrine isn't working as planned. You're only trading range/power for more ammo and lighter weight and there's a limit to how far you can go with that and retain battlefield utility.

 

[TAB]

if the 5.7 was a great combat round, wouldn't all of the worlds armys be beating down FNs door for it?

 

[elmerfudd]

I don't think that anyone is fielding a great combat round at this point in time. The 7.62x39 probably comes closest, but it's got a rainbow like trajectory and tends to just punch 30 caliber holes. The 5.56 is pretty good when it fragments, but it's lacking in penetration and just makes a .22 caliber hole when it doesn't fragment. The 5.45 is just a 5.56 that tumbles better but doesn't fragment. The 7.62x51 and 7.62x54R have great ballistics and stopping power, but they also weigh too much and recoil too much.

What is needed is a midpower round like the 6.8 that both tumbles quickly and fragments nearly every time.

 

[Eric F]

We Have A Winner

if the 5.7 was a great combat round, wouldn't all of the worlds armys be beating down FNs door for it?

DING DING DING
Give that member a cigar!

 

[Funderb]

why not 5.7x35?
nice round in between! bigger diameter, and still fun!


haha I love throwing monkey wrenches in glass rooms.

 

[Gunnerpalace]

if the 5.7 was a great combat round, wouldn't all of the worlds armys be beating down FNs door for it?

Secret Service uses it, so if must not be THAT wimpy.

And if a 5 . 7 is a glorified .22 so is a 5 .56.

 

[TAB]

yes but the Secert service is not the miltary, they have a niche they wanted filled, the P90 filled that niche... Something you can conceal, high capicty, short ranged, not much in the way of penatration, low recoil, can defeat body armor with the right ammo... etc

Sounds like a great weapon to protect some one in a tight spaces. I bet they still use thier mp5.

Does not mean its a great combat round.

 

[Gunnerpalace]

Does not mean its a great combat round

That's true.

 

[TexasRifleman]

Does not mean its a great combat round
.....
That's true.

Doesn't mean it's NOT a great combat round either.

It has it's place; a submachinegun round when a high number of rounds on target in a very short timeframe is called for, with the chance that the hostile is wearing armor.

In that usage there probably isn't a better round out there to meet those requirements.

I don't think anyone is dumb enough to think that it's some kind of Battle Rifle round.

 

[GunTech]

The 5.7mm was designed as a close combat round.

No, the 5.7 was designed as a pistol replacement for troops that don;t have combat MOS. It was not designed for close combat. It was designed to replace 9mm ball from a handgun.

 

[GunTech]

MTMilitiaman the 5.56 was designed to be a 500m combat round. that is what it was built for.

Actually, the 5.56x45 was really meant as a 300 yard round. The designed was heavily influenced by the Hall study, which was itself influenced by the Hitchman report which noted that 90% of all infantry small arms fire including machineguns occurred at 300 yards or less, and that virtually all fire occurred at 500 yards or less for reasons that has more to do with the realities of combat than the capability of the weapon.

However, the Army has continually been pushing the requirements for the 5.56x45 to longer and longer range, while the reality is that bullet fragmentation is virtually non-existant past about 150 yards, and it is this behavior that makes the 5.56x45 disproportionately lethal for it's size. In Vietnam the 5.56x45 was actually shown to be 11% more lethal than the 7.62x51 - exactly because most combat operations were meeting engagements and ambushes at relatively short range.

Now with the popularity of the M4, velocities are reduced and the fragmentation range of the M855 is closer to 100 yards, beyond which the 5.56 behaves like any other ball projectile.

 

[GunTech]

What is needed is a midpower round like the 6.8 that both tumbles quickly and fragments nearly every time.

The 6.8 is limited in that it is restricted by the M16 magazine. Bullets are short, and therefor BC is poor. Fragmenting rounds seem like a great idea, but the problem is that then penetration suffers.

No matter what you do, you are going to have to compromise. You'll never get something for nothing.

As has been discussed in the 'ultimate combat round' thread, if you split the difference between 7.62x51 and 5.56x45 you end up with a 6.5mm 108 gn bullet at about 2850 fps. This is very doable although an ideal case will probably not fit in the M16 platform. The 6.5 Grendel comes close, but requires a 24 inch barrel to achieve close to the required velocities and the case shape is probably not ideal for automatic and particularly belt fed weapons

If you free the cartridge from the constraints of the M16 platform, the required performance can be has in a cartridge with moderate shoulder, good case taper and decent size and weigh. Given the excellent BC values of the 6.5, you can actually better the long range performamce of both the M80 ball and M118LR special ball but this requires heavier bullets with higher recoil. These bullets will also have very high sectional density compared to 5.56 and even 7.62 and so should have good performance against barriers.

The ultimate combat round thread can be found here:

http://www.thehighroad.org/showthread.php?t=292713

 

[TexasRifleman]

No, the 5.7 was designed as a pistol replacement for troops that don;t have combat MOS. It was not designed for close combat. It was designed to replace 9mm ball from a handgun.

The first public demonstrations of the x28 were done with a P90, not a handgun.

The x28 came out in initial public testing around 1995, 96.

The Five Seven handgun did not come out til around 99, 2000.

The round was developed for the P90 PDW, then later adapted to handguns when agencies wanted their SMGs and handguns to use the same round.

 

[GunTech]

Here's something to think about vis-a-vis 5.7x28. How many people think the 22 hornet would make a good combat round?

22 hornet will launch a 32gn projectile at 3000 fps
5.7x28 can only 2350 fps with the same bullet weight (SS190AP)

 

[GunTech]

The first public demonstrations of the x28 were done with a P90, not a handgun.

The x28 came out in initial public testing around 1995, 96.

The Five Seven handgun did not come out til around 99, 2000.

The round was developed for the P90 PDW, then later adapted to handguns when agencies wanted their SMGs and handguns to use the same round.

Exactly, and the PDW was supposed to replace the handgun - hence the 5.7x28 (in the PDW) was meant to replace the 9mm pistol

 

[TexasRifleman]

Here's something to think about vis-a-vis 5.7x28. How many people think the 22 hornet would make a good combat round?

Here's something to think about...

Is anyone making a 50 round capacity submachinegun shooting 22 Hornet that uses a bullet designed to penetrate body armor?

You're hung up on velocity and energy, but that's not really what this round was developed for.

It was specifically designed for use in a submachinegun with a bullet designed to penetrate body armor.

 

[GunTech]

Just for reference, I thought this comparison would be illustrative.

From left to right:

5.7x28, 22 K Hornet, 5.56x45, 6.8 SPC, 6.5 Grendel, 6.5x45 Cz, 7.62x51

 

[rbernie]

I don't think anyone is dumb enough to think that it's some kind of Battle Rifle round.

Well, from post #1:

The military would just have the 5.7x28, with larger 7.62x51 and 12.7x99 machine guns providing support from machine guns and sniper rifles.

 

[TexasRifleman]

Well, from post #1:

Exactly, the OP didn't intend this as an argument for the x28 as a main battle round, he asked why the things that made the 5.56 appealing would not simarly apply to x28.

I got the idea he was poo pooing the reasons to move to 5.56 in the first place.

If the arguments for moving from .308 to 5.56 were valid, why not apply the same thing to x28, then down and smaller from there to absurdity.

And, if those reasons don't apply in the 5.56 vs x28 argument then maybe they didn't apply so much in the .308 vs 5.56 argument.

Maybe I read it wrong but I didn't get the idea he was proposing x28 as the end all and be all so much as questioning the original reasons for abandoning .308

 

[PercyShelley]

Laugh though we may now, HK looked very seriously at 4.6mm assault rifles (the G11 and HK36) before they developed the MP7. Some hyper-velocity gimmick you protest? No, both of those rounds developed substantially less velocity than 5.56 NATO ball loads in addition to having smaller, lighter bullets.

Go figure.