BF2S Forums 5.56 v.s. 5.45 Velocity

And what is the groove pattern on the 5.45's barrel? Don't forget the 5.56 rotates a lot slower than most rounds in order to cause maximimum effectiveness on impact.

deeznutz1245 wrote:

And what is the groove pattern on the 5.45's barrel? Don't forget the 5.56 rotates a lot slower than most rounds in order to cause maximimum effectiveness on impact.

pfft.
That why they have to shoot somebody six times to drop them? The 223 round makes nice clean little holes.

Lai wrote:

Ottomania wrote:

5.56 is NATO standart. You will have a chance of picking up enemy munitions during combat. Better than surrendering with empty magazines.

I'm afraid not as, at least to my knowledge, Russian made 5.56 arms are not STANAG compatible. You'd have to pick up enemy mags, remove the rounds from the mag one by one, load them into a charger one by one, and charge them in one of your own emptied Russian mags, and all during combat. In my opnion that pretty much does it for 'combat pickup advantage'.

deeznutz1245 wrote:

And what is the groove pattern on the 5.45's barrel? Don't forget the 5.56 rotates a lot slower than most rounds in order to cause maximimum effectiveness on impact.

I figured the trick's in the rifling, but frankly I assume that if they bother to develop a 5.56 version of the weapon (which should be coming with a different bore anyway), they'd optimized the barrel for that type of round.

ATG wrote:

deeznutz1245 wrote:

And what is the groove pattern on the 5.45's barrel? Don't forget the 5.56 rotates a lot slower than most rounds in order to cause maximimum effectiveness on impact.

pfft.
That why they have to shoot somebody six times to drop them? The 223 round makes nice clean little holes.

Maximum effectiveness possible with said cartridge that is. The fact that the 5.56 in principle is fail, is a whole other issue. Personally I think moving to a light (I won't say 'intermediate' since I associate that with the rejected .280 British, 6.8 SPC or 6.5 Grendel) cartridge as a standard issue military round has been one of the bigger mistakes in military history. If I had to pick to, I'd rather have the 5.45 than the 5.56, as by design the first (not really/really not a FMJ) has more stopping power. Also the main, if not only, advantage of light calibre military rounds is low recoil. As such I'd go with the cartridge with the lowest recoil as all the other properties are shit anyway.

And to counter that last argument: most 5.56 weapons aren't used in full auto mode, only 3-shot or semi. Ergo, there really isn't any advantage except maybe the .5 kilo difference between carrying 4 mags of 5.45 and the same of 5.56.

Last edited by TSI (2009-02-01 11:23:16)

TSI wrote:

And to counter that last argument: most 5.56 weapons aren't used in full auto mode, only 3-shot or semi. Ergo, there really isn't any advantage except maybe the .5 kilo difference between carrying 4 mags of 5.45 and the same of 5.56.

Well, the idea is that, compared to full power 7.62(x51) loads, for the same amount of mass, you can carry rougly more bullets (about 50% me thinks). However, compared to intermediate Russian 7.62x39, the gain could be considered trivial: both 5.56 M16 mags and  banana 7.62 AK mags generally carry 30 rounds. In fact, original AR15 mags only carried about 25 rounds and some modern AK mags carry 40-45 rounds. French 5.56 FAMAS F1 mags still carry only 25 rounds. Even though the newer FAMAS G2 accepts STANAG mags, the French seem to stick with thier own 25 caps; I presume because they're easier to load and less prone to feed jams (after all, the 5.56 has a case that isn't nearly as tapered as the 7.62x39 and wasn't intended for even slightly curved magazines).

Considering the burst limitations I have to disagree with you though. You really can't blame the cartridge for NATO countries (especially the US) acting cheap on ammo. That said, I'm interested to see how the 5.56 fares recoil wise against a 7.62x39 fired from an AEK with muzzle brake and counter balancing system. Due to the Russians coming up with their 5.45, their old 7.62x39 is often compared with NATO's old 7.62x51. However isn't the recoil of the 7.62x39 much smaller anyway, as the 7.62x51 would be more in line with 7.62x53 rimmed and .30-06?

deeznutz1245 wrote:

ATG wrote:

deeznutz1245 wrote:

And what is the groove pattern on the 5.45's barrel? Don't forget the 5.56 rotates a lot slower than most rounds in order to cause maximimum effectiveness on impact.

pfft.
That why they have to shoot somebody six times to drop them? The 223 round makes nice clean little holes.

Im not talking about your AR-15 buddy. I have inspected my um, work, and there were no clean little holes.

Ok,..

So, what kind of ammo did you use and from what range did you fire?

The 5.45 has a hollow core in the nose that expands causing massive wounds. They have reports from the Soviet invasion of Afghanistan the Mujaheddin fearing that rounds wounds.

Lai wrote:

Ok,..
So, what kind of ammo did you use and from what range did you fire?

I am a US Marine.

Last edited by deeznutz1245 (2009-02-01 14:33:10)

FatherTed wrote:

Don't they use the 5.56 because it's a (fairly) clean kill?

From what I heard, it was because it doesn't kill. It wounds.

A wounded soldier is more damaging to an army than a dead one: cries of the wounded (psychological effect), evac/medical care ($$ and maybe buddies killed trying to save him), rehabilitation+equipment.

A dead soldier needs a guy to get his body, and a coffin. End of story, as the payments to his family are really insignificant in the long run.

deeznutz1245 wrote:

Lai wrote:

Ok,..
So, what kind of ammo did you use and from what range did you fire?

I am a US Marine.

Fine, so that leaves the range,.. ?

TSI wrote:

Well, we're in agreement. I'm pointing out that the 5.56's saving feature doesn't exist--that's its only advantage is pointless.

I'm not talking about being cheap on ammo. What I'm saying is that for accuracy's sake NATO (or at least US+UK) prefer using bursts and single fire. Why? Because it's supposedly more accurate--you get to reset after each shot/each set of 3 shots.

There really isn't any difference in recoil between a 7.62x39, a 5.45 or a 5.56 after one shot or three shots. You get to reset anyways. Thus, the argument that there's less recoil stands up to little scrutiny.

Hence, the 5.45 is better, nothing more to say.

True, especially on your last statement. However, to my knowledge burst mode was initially not implemented for accuracy sake but for the sake of conserving ammo as it forces the operator to 'take a breath' in between and prevents them from 'going Rambo' in panic. Exactly the same reason the original select fire M14's were fixed on semi during Viêt Nam; a trained operator could use the select fire M14 to fire three to four round bursts fairly well and the full power cartridge not being deflected by brush would have come in rather handy in jungle warfare (as well as the M14's open action not constantly jamming). In other words; from a tactical perspective limiting the amount op consecutive rounds an operator can fire is generally plain stupid. Exceptions of course are the FAMAS which comes standard with a bipod and has a high ROF and the astounding two rounds burst of the AN-94 'Nikonov', but then again both of those rifles also have a full auto mode.

SgtHeihn wrote:

The 5.45 has a hollow core in the nose that expands causing massive wounds. They have reports from the Soviet invasion of Afghanistan the Mujaheddin fearing that rounds wounds.

The Soviets didn't like it though as it didn't do as well against infantry in cover. Logically as the bullet was designed to deform and transmit as much kinetic energy as possible, it seldom ricocheted.

TSI wrote:

FatherTed wrote:

Don't they use the 5.56 because it's a (fairly) clean kill?

From what I heard, it was because it doesn't kill. It wounds.

A wounded soldier is more damaging to an army than a dead one: cries of the wounded (psychological effect), evac/medical care ($$ and maybe buddies killed trying to save him), rehabilitation+equipment.

A dead soldier needs a guy to get his body, and a coffin. End of story, as the payments to his family are really insignificant in the long run.

Actually in some cases its payments FROM his family. During the Indonesian war of independence, whenever they killed a Dutch soldier and his comrades had to leave his body (and evidently his gear), his family would recieve a bill from defense for 'your son's borrowed rifle we couldn't retrieve'. (...) disgusting in my opinion.

On topic, the 5.56 could be made more damaging (like the 5.45), but it wouldn't comply to the The Hague Convention of 1899, which prohibits the use of 'exploding' ammunition below a certain diameter against infantry (so no Godwyn pattern bolters either). It was considered inhumane. In my opinion this is bullshit as they couldn't have anticipated on the dynamics of 21st century warfare back then and there is nothing more humane about having someone bleed to death or have a solid bulet made bouncing through his body compared to an expanding bullets that kills faster.

The argument of wounding being more damaging to an army goes for landmines, but not for bullets. In a person v.s. person situation you want the enemy to drop and be sure that he's no longer a thread. You don't want him to shout 'ouch my arm, better let the doc take a look at it' and thinking 'meanwhile, waiting, I'll draw my pistol with my other arm and waste the guy who did it'.

SgtHeihn wrote:

Oh and if the bean counters would have left the 1/10th twist in the M16 instead of switching to 1/7th twist (to make the long range shooters happy), we would not have the stopping power complaints that we are having now.

Actually, the higher twist rate is much better for lethality. The old myth of the Viet Nam era "tumbling bullet" causing such horrific damage was, to put it politely, overstated.  A bullet that tumbles so easily on impact is, by definition, so close to unstable in flight that ANY little upset is going to trash it's accuracy.. any variation on atmospheric temperature will push it into instability (ask a Korean War vet what cold weather does to marginally stable ammo).. any variation on humidity (alot of that in Viet Nam).

- Higher rotational speeds = better detonation in soft targets (people). A large part of the reason the Mk262 ammo is so over-pressure/hot is to keep the velocity up above the critical detonation speed, for a far enough engagement range (125m for M4, 200m for M16 ?), when launched from the stubby little M4 barrels.  I think that critical speed is 2200fps, but I may be remembering the wrong numbers.

- Faster twist needed to stabilize longer (heavier) bullets (77gr Sierra MK in the Mk262 rounds). 

- Longer, heavier bullets at higher speed = better barrier penetration (armor, cover, etc) = bad guys can't hide behind "tin-foil" and be safe from M-16, M-4 and M-249 gunners.

- Longer, heavier bullets = higher BC (Ballistic Coefficient) = higher retained energy at ranges beyond 300m.  If the round goes below Mach 1.1, it starts getting into transonic turbulence, totally destroying the accuracy of nearly any rifle bullet.  From memory, Mk262 goes transonic at 850m, M855 at 650m.

In short, a long/fast/heavy bullet is the best you're going to get if you're forced to use 5.56x45 NATO.  Better range, better kinetic energy into targets, better barrier penetration, better wind-drift characteristics, and (if loaded right) more consistent velocity/trajectory from round to round.

SgtHeihn wrote:

The 5.45 has a hollow core in the nose that expands causing massive wounds. They have reports from the Soviet invasion of Afghanistan the Mujaheddin fearing that rounds wounds.

To add to that description;
If it's the same Russian 5.45mm that I'm thinking of, it's much worse than a normal hollow point (not to be confused with "open tip match").
In the Russian ammo, the lighter outer copper shell of the bullet slows on contact with the target, while a steel/lead core comes loose inside and continues moving forward in the bullet - opening up the front of the copper jacket/shell, causing a larger frontal area ("mushroom"), causing the round to slow down even faster, and hence causing a very large, very fast dump of kinetic energy into the target.

IF the target is wearing armor, or behind steel plate, the copper jacket stops on the outside of the armor, while the lead/steel core continues moving.  The heavy lead core drives the steel penetrator through the armor, like a hammer pounding a nail - and the steel penetrator does whatever damage it can to the target.

That's the theory anyways.  Dunno how reliable that whole process is in actual use.  I'll stick to good old American Nosler ballistic tips for quick-expansion rounds.

Edit: Here's a good paper on the topic;
Small Caliber Lethality: 5.56mm Performance in CQB

Last edited by rdx-fx (2009-02-01 18:15:05)

Lai wrote:

Even though the 5.56 evidently has a larger diameter, I thought the 'standard' 5,45 round was slightly heavier, due to the steel core penetrator. In any case I expected the standard 5.56 to be faster, but this shows that fired from the same platform the 5.45 is about 3.53% faster.

Any opinion/comments?

The "Standard" 5.56x45mm NATO ammo ranges in bullet weight from 55gr (older M193) to 77gr (Mk262). They leave the muzzle at roughly 3200 fps(M193) and 2800 fps (mk262).

The differences in weight and speed available for 5.56 is larger than the minor listed difference between the book-5.56 and book-5.45 you listed. 

Hell, the temperature of the ammo can cause more than a 3.53% change in velocity in most ammo..  Hot desert day in Iraqistan, versus cold winter day at a Swiss range.

And, the 5.56x45 M855 (62gr, 3000fps launch) round ALSO has a steel penetrator.

The short point I'm getting at, is that the differences in weight/speed between them are trivial.  In practice, environmental conditions have a much larger effect on bullet performance than those listed specs.

In practice, I wouldn't remember the exact ballistics table listed 10mph drift for a mk262, I'd remember;
"One MOA per 100 yards range. Plus/Minus 5% step per 100yd off of 400yd"
400=4.0, 300=(3.0-0.15)=2.75, 200=(2.0-0.20)=1.80, 500=(5.0+0.25)=5.25, 800=(8.0+1.6)=9.6  -- going by my in-the-head easy-to-remember calculation.
If in a big hurry, just use "1 moa per 100yd per 10mph wind".  400yd, 10mph wind = 4.0 MOA .. 800yd, 10mph wind = 8.0 MOA.


[note: this is all from memory, so.. I might be off on some of the book-listed muzzle velocity numbers.  Someone else can dig up the book-listed Mk262 drift numbers, if they want to check my memory.]

Just comparing directly

5.45x39
50 gr FMJ
mv 3,000 ft/s
me 971 ft·lbf
Barrel 1/10

5.56x45
62 gr SS109 FMJBT
mv 3,100 ft/s
me 1,303 ft·lbf

63 gr DM11 FMJBT
mv 3,070 ft/
me 1,325 ft·lbf

Barrel 1/7 or 1/9

5.56 would seem to have a slight edge on paper for likely accuracy and range, and a good deal more kinetic energy.
In practice it probably comes down to bullet design and barrel length.

Last edited by Dilbert_X (2009-02-02 15:17:58)

Lai wrote:

Wind drift characteristic are said to have been downright terrible with the original Viêt Nam era .223. With the newer Belgian designed 5.56 rounds mass was increased, but in relatively long range windy scenario's (Afghanistan anyone?) wind drift characteristics are still far from perfect. There's a sense of irony in the fact that the M16/5.56 combo's main advantage over the good old AK is at ranges beyond 300 meters, which is exactly when the 5.56's deficiencies begin to surface. Also, as SgtHeihn has pointed out, the shift to a lighter cartridge was made, bearing in mind that most confrontations occur within a 300 meter range.

In a 10mph constant wind, the 5.56, firing a 77gr round, drifts 10moa at 800yd - compared to the 7.62 NATO (M118LR 175gr SMK) drifting 8moa at 800yd.  The AK is lucky to hit the broad side of a barn at 800yd.  The Mk262 ammo really did bring up the long range performance of the 5.56

It is fairly ironic that the M16 was originally designed as a rapid-fire under-300m "Sturmgewehr" - and now it has evolved into the 750m+ designated marksman rifles (or 500m issue M16a3/a4).  Still too small of a caliber for guaranteed body-shot kills, but it can accurately poke holes in things anywhere out to 750m. AND it can do sustained controllable on-target automatic fire in CQB, AND it is much easier to wield in close quarters room clearing than an M14 or M60.

It's not a perfect rifle, but I'd rather have a M16a4 than an AK.
If I could get a "M16a5" in 6.5 Grendel, that'd be even better though.

And, as a minor point, the shooting conditions in Afghanistan are often less than ideal for any bullet.  Turbulent, twisting winds - angled shots requiring memorization of sine tables - barometric changes from temperature AND elevation changing effective range & drift numbers - screwy mirages from strange combinations of atmosphere/ground temperatures.  You're having a good day if the first round goes where you told it to go.