5.56x45 or 7.62x39?

[Ignition Override]

This is posted ----only for entertainment----. No hidden agenda, nothing "between the lines".

His channel might still be called "Gun Time With Brandon". Kirsti actually is a pretty good shot in other videos.

 

[valnar]

Thanks for providing the weights of the individual cartridges.

The BRL Bio-Physics Division Provisional Personnel Incapacitation models, based upon the analysis of 7,898 WDMET (Wound Data Munitions Effectiveness Team) combat wound data, were used by the US ARMY to match the P[I/H] of the 5.56x45mm M193 to the P[I/H] of the 7.62x39mm M43.

The 29.4% weight savings of the 5.56x45mm M193 over the 7.62x39 M43 (12 grams vs. 17 grams, respectively) makes the 5.56x45mm the more preferable of the two cartridges since both cartridges have equivalent P[I/H] and T[I/H] values.

The T[I/H] (Expected Time to Incapacitation, measured in seconds) was computed using the minimum ΔE15 necessary to achieve a 100.00% P[I/H] scaled against a nominal 1-second time constant.

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I'd like to see someone walk around for 4 seconds after being hit with a .50 BMG.

I just want to note that the chart appears to be using a 20-22" barrel(??) for those XM193 velocities. I think 16" is closer 3000-3100, although it probably makes little difference.




I've seen this before and it always surprises me. One that 5.56 is so damaging, and two that 7.62x39 is approved for deer hunting in most places, but .223 is NOT. I mean, if it does this....

 

[BreechFace]

View attachment 1144033

What distance is the encounter, seems a very important variable to include in this study that is missing. The XM193 velocities seem very optimistic out of a 16", typically this is around 3,050-3,100fps. The velocities given for the M43, 7.62x39 were pretty accurate out of a 16".

No doubt in a protracted firefight 5.56 has it's distinct advantages, due to weight and especially with distances 250 yards and out. But it is my contention that at ranges sub-250 yards the x39 for energy on target and incapacitation with good ammo such as the 8m3 is very effective.

Would be curious to run this same tests with 8m3 (124gr) ammo which fragments. Velocity averages ~2,440fps out of a 16" AK. If one is to carry a self defense round in an AK it's hard to argue with the 8m3, it's hot ammo and devastating.

 

[481]

I'd like to see someone walk around for 4 seconds after being hit with a .50 BMG.

I just want to note that the chart appears to be using a 20-22" barrel(??) for those XM193 velocities. I think 16" is closer 3000-3100, although it probably makes little difference.

View attachment 1144122

I've seen this before and it always surprises me. One that 5.56 is so damaging, and two that 7.62x39 is approved for deer hunting in most places, but .223 is NOT. I mean, if it does this....

Same here. I always find this stuff to be fascinating—it never gets old.

Resins, soaps, waxes, and other plastic mediums are great for capturing the temporary cavity dimensions which may, or may not, reflect dynamic pressure sufficient to exceed the yield strength of the soft tissues surrounding the path of the projectile.

The muzzle velocities are taken from common literature/sources on the topic. I agree that from a 16'' barrel that 5.56x45 M193 muzzle velocity would be on the order of 3,000 - 3,100 fps but, as you correctly surmise, the difference in P[I/H] and T[I/H] between muzzle velocities of 3,281 fps and 3,000 fps for the M193 is 56.59% (-5.42% ) and 9.42 seconds (0.81 seconds), respectively is fairly minor.

 

[WrongHanded]

View attachment 1144103

Okay, so let's discuss the images here. This is "resin"? How does that compare to 10% ballistic gel, or to the human body?

 

[481]

What distance is the encounter, seems a very important variable to include in this study that is missing. The XM193 velocities seem very optimistic out of a 16", typically this is around 3,050-3,100fps. The velocities given for the M43, 7.62x39 were pretty accurate out of a 16".

No doubt in a protracted firefight 5.56 has it's distinct advantages, due to weight and especially with distances 250 yards and out. But it is my contention that at ranges sub-250 yards the x39 for energy on target and incapacitation with good ammo such as the 8m3 is very effective.

Would be curious to run this same tests with 8m3 (124gr) ammo which fragments. Velocity averages ~2,440fps out of a 16" AK. If one is to carry a self defense round in an AK it's hard to argue with the 8m3, it's hot ammo and devastating.

View attachment 1144130

You're right. Striking velocity decreases over range and would have a significant effect upon the P[I/H] and T[I/H] of both rounds.

Just the same, it would be interesting to graph that for any given cartridge.

Where only ball rounds were modeled the chart above, the 8M3 definitely ''brings more to the table'' in terms of terminal performance by way of expansion/fragmentation. That effect is within the ability of the modeling that I am using, but I didn't pursue it in my prior post because I didn't want to ''overwhelm'' anyone with a massive amount of analytical data.

 

[BreechFace]

You're right. Striking velocity decreases over range and would have a significant effect upon the P[I/H] and T[I/H] of both rounds.

Just the same, it would be interesting to graph that for any given cartridge.

Where only ball rounds were modeled the chart above, the 8M3 definitely ''brings more to the table'' in terms of terminal performance by way of expansion/fragmentation. That effect is within the ability of the modeling that I am using, but I didn't pursue it in my prior post because I didn't want to ''overwhelm'' anyone with a massive amount of analytical data.

I bring up striking distance just as a curiosity, as M193 will fail to fragment at distance (see below), I've seen studies this is as close as 150m out of a 16" barrel and 100m out of an M4 14.5" barrel. At which point it's damage is done more with tumbling and limited fragmentation. This is why there were reports of issues of effectiveness at distance in the GWOT with the M4's and M193 or M855 (which has lower fragmentation threshold ranges than M193) which is why the M855A1 was developed.

I think the big disconnect in comparing m193 and M43 is that they damage in very different ways. The M193 while ball ammo, fragments causing damage; whereas the M43 tumbles causing damage. That is why I keep bringing up 8M3 because it more of an apples to apples on terminal wounding as they both fragment. But this gets away from the intent of this thread as the desire is to compare FMJ's to each other, and technically 8M3 is not as it has a cavity at the tip to promote fragmentation.

 

[C-grunt]

Okay, so let's discuss the images here. This is "resin"? How does that compare to 10% ballistic gel, or to the human body?

From my experience and from talking to medics from Iraq/Afghanistan and medical personnel state side.... at close range there is very little difference.

Both rounds will yaw regularly and create very horrific wounds. The 5.56 will usually fragment as well.

I've seen the 7.62x39 perform somewhat inconsistent and sometimes just blow straight through, more often than 5.56. I think this has more to do with the quality of the ammo observed vs the design of the round. I have never seen either round "ice pick" even when going straight through. They still did substantial damage (at close range).

At longer range, say 150 yards and beyond, the 5.56 was more effective. The 5.56 was still well above the velocity zone where temprary cavitation produced significant wounds. At this range the 7.62x39 would still easily plough all the way through you, but it lacked much of the "rifle wounds" that it showed at close range.

 

[BreechFace]

The M193 when used with the M16, 20" barrel was a very effective round with great fragmentation to 200m+, as the military started shortening their rifles down the advantages of a small bore start to diminish with it's velocity. A larger bore will always do better at getting to greater velocities and match energies than a smaller bore as the barrel length decreases. There is more base diameter for the gases to push against. There is greater benefits for a 224" projectile to gain over a .311" projectile with longer barrel lengths.

 

[BreechFace]

From my experience and from talking to medics from Iraq/Afghanistan and medical personnel state side.... at close range there is very little difference.

Both rounds will yaw regularly and create very horrific wounds. The 5.56 will usually fragment as well.

From my non-personal experience, I would agree. You are closer to real life experiences than I am. And thank you for your service and experiences.

I've seen the 7.62x39 perform sunshade inconsistent and sometimes just blow straight through, more often than 5.56. I think this has more to do with the quality of the ammo observed vs the design of the round. I have never seen either round "ice pick" even when going straight through. They still did substantial damage (at close range).

Physics would lead one to believe ice picking with a spire point is impossible, as a bullet whose base is much heavier than it's tip when being distrupted will tumble. So no surprise that no "ice picks" were witnessed. In fact, voids are created at the bullet tips on some projectiles to promote early tumbling.

At longer range, say 150 yards and beyond, the 5.56 was more effective. The 5.56 was still well above the velocity zone where temprary cavitation produced significant wounds. At this range the 7.62x39 would still easily plough all the way through you, but it lacked much of the "rifle wounds" that it showed at close range.

Was this with M16's or M4's? Just curious on barrel length.

 

[C-grunt]

The difference between a 14.5 and 16 inch barrel is around 50-75 FPS. Using Strelok Pro, the change in distance to reach 2700 FPS with M193 is about 15 yards. Both right around 100 yards.

 

[481]

I bring up striking distance just as a curiosity, as M193 will fail to fragment at distance (see below), I've seen studies this is as close as 150m out of a 16" barrel and 100m out of an M4 14.5" barrel. At which point it's damage is done more with tumbling and limited fragmentation. This is why there were reports of issues of effectiveness at distance in the GWOT with the M4's and M193 or M855 (which has lower fragmentation threshold ranges than M193) which is why the M855A1 was developed.

I think the big disconnect in comparing m193 and M43 is that they damage in very different ways. The M193 while ball ammo, fragments causing damage; whereas the M43 tumbles causing damage. That is why I keep bringing up 8M3 because it more of an apples to apples on terminal wounding as they both fragment. But this gets away from the intent of this thread as the desire is to compare FMJ's to each other, and technically 8M3 is not as it has a cavity at the tip to promote fragmentation.

View attachment 1144149

Most definitely, agree.

The three currently existing BRL energy-based provisional incapacitation models are still used by the military to develop and assess not only ball ammo, but fragmenting munitions, too. Considering how projectiles behave mechanically within the target is within the models' capabilities, but it gets considerably more complex to process. The 8m3 is one such example.

As for ball ammo, which most militaries are restricted to under convention and legal constraint, these models offer a unique way of evaluating them.

For example, using the 1968 provisional incapacitation P[I/H] model, even at the relatively 'sedate' velocities of domestic commercial offerings, the .45ACP (230-grain ball @ 825 fps) and 9mm (124-grain ball @ 1,100 fps) offer very close terminal performance to one another, with a very, very slight edge going to the 9mm.

.45ACP 230-grain ball @ 825 fps: P[I/H]: 31.13% T[I/H]: 15.28 seconds

9mm 124-grain ball @ 1,100 fps: P[I/H]: 31.34% T[I/H]: 15.21 seconds

Despite the ''intellectual heartburn'' experienced by some very prominent researchers in the field of terminal ballistics, the fact is that the US ARMY's BRL Bio-Physics Division at Aberdeen Proving Grounds was able to design a round that successfully matched the battlefield capabilities of the 7.62x62 using those models. Tons (literally) of paper and ink have been spent denying the historical fact that the energy-based (ΔE15) provisional incapacitation models were a tremendously effective methodology in matching our battlefield adversaries' small arms munitions, yet the Soviets must've seen the value in doing so since they later fielded the 5.45x39 in response to the 5.56x45. And, yet, here we are. The 5.56x45 still reigns as the dominant small arms cartridge in the US military with other developments in the pipeline.

Speaking of that...

What I find really interesting is that the Chinese must've also decided that energy-based (ΔE15) provisional incapacitation P[I/H] models were worth the effort. In the 1990s the Chinese fielded the 5.8x42 DBP87 that compares quite favorably with the 5.56x45 M193 and M855 as well as the 7.62x39 M43 and M67. With the US military developing the 6.8x51 (or the .277 Fury in civilian guise), it seems that the US military is once again ''setting aside'' these experts' opinions on the energy-based provisional incapacitation models and developing a new cartridge that offers (slightly) greater terminal performance than the Chinese DBP87—using these same models.

 

[C-grunt]

Physics would lead one to believe ice picking with a spire point is impossible, as a bullet whose base is much heavier than it's tip when being distrupted will tumble. So no surprise that no "ice picks" were witnessed.



Was this with M16's or M4's? Just curious on barrel length.

I've definitely seen wounds where the bullet didn't tumble. What I mean when I say they didn't "ice pick" was when some people say they just prodice a caliber wide hole with little or or damage outside the wound. I've seen CT scan of rounds that didn't tumble, but they still produced tearing outside the bullet path. If not exactly common, but Ive seen it more than once.

My experience is with both the M16 and the M4. I never noticed any difference at common combat distance, say 200 meters and in. The only 5.56 shot I can confirm at greater distance was the guy I shot at just over 400 meters with the SDM-R. But that was with M262. We also shot guys at distance in 2003 with the M249, but I was never able to go do any sort of assessment on those guys.

 

[BreechFace]

The difference between a 14.5 and 16 inch barrel is around 50-75 FPS. Using Strelok Pro, the change in distance to reach 2700 FPS with M193 is about 15 yards. Both right around 100 yards.

But marines were using M16A4's up until 2016, at which point there were sufficient M4's to move the M16A4's into a support role correct?

So a 20" barrel versus 14.5" barrel is pretty significant velocity difference and thus threshold for fragmentation with projectiles used.

EDIT: responded before you response above, answered my question.

 

[481]

Physics would lead one to believe ice picking with a spire point is impossible, as a bullet whose base is much heavier than it's tip when being distrupted will tumble. So no surprise that no "ice picks" were witnessed. In fact, voids are created at the bullet tips on some projectiles to promote early tumbling.

Yep.

It's all about correctly managing the center of pressure and center of gravity. Mix 'em up and instability is sure to follow.

 

[C-grunt]

But marines were using M16A4's up until 2016, at which point there were sufficient M4's to move the M16A4's into a support role correct?

So a 20" barrel versus 14.5" barrel is pretty significant velocity difference and thus threshold for fragmentation with projectiles used.

EDIT: responded before you response above, answered my question.

My unit used mostly M16A4s until after I got out. They didn't fully switch to M4 until around 2010 I believe.

Funny anecdote that breaks internet lore. My brother in law was a Marine Infantryman the same time I was an Army Infantryman. I carried a M16A4 and he carried a M4.

 

[CoalTrain49]

View attachment 1144103

It'll blow your lungs out.

 

[BreechFace]

It'll blow your lungs out.

Incorrect, that's 9mm. Our president is an expert on such things.

 

[d2wing]

I've definitely seen wounds where the bullet didn't tumble. What I mean when I say they didn't "ice pick" was when some people say they just prodice a caliber wide hole with little or or damage outside the wound. I've seen CT scan of rounds that didn't tumble, but they still produced tearing outside the bullet path. If not exactly common, but Ive seen it more than once.

My experience is with both the M16 and the M4. I never noticed any difference at common combat distance, say 200 meters and in. The only 5.56 shot I can confirm at greater distance was the guy I shot at just over 400 meters with the SDM-R. But that was with M262. We also shot guys at distance in 2003 with the M249, but I was never able to go do any sort of assessment on those guys.

Much of the Ice pick idea is entirely false. The faster the a bullet travels, the greater the resistance in flesh much like in liquid, the wider the wound channel. Only slow rounds will travel through flesh without a wide wound channel. Much of this misconception comes from the falsehood that bullets only damage the tissue that they touch and velocity and energy doesn't matter. The widely read person that spread this misinformation was sued in court and lost. That person had no real qualifications but widely claimed falsely that he was president of an institute that was just him.

 

[481]

From my experience and from talking to medics from Iraq/Afghanistan and medical personnel state side.... at close range there is very little difference.

Both rounds will yaw regularly and create very horrific wounds. The 5.56 will usually fragment as well.

I've seen the 7.62x39 perform somewhat inconsistent and sometimes just blow straight through, more often than 5.56. I think this has more to do with the quality of the ammo observed vs the design of the round. I have never seen either round "ice pick" even when going straight through. They still did substantial damage (at close range).

At longer range, say 150 yards and beyond, the 5.56 was more effective. The 5.56 was still well above the velocity zone where temporary cavitation produced significant wounds. At this range the 7.62x39 would still easily plough all the way through you, but it lacked much of the "rifle wounds" that it showed at close range.

Your personal experience is an interesting one that correlates well with the BRL energy-based (ΔE15) provisional incapacitation P[I/H] models' predictions.

Considering the terminal performance of the 5.56x45 M855A1 (62 grain FMJ @ 3,100 fps) and the 7.62x39 M67 (123 grain FMJ @ 2,329 fps) when fired from 16-inch barrels:

At ranges of 50m and 300m, your experience matches what the 1968 BRL energy-based (ΔE15) provisional incapacitation model (developed by L M Sturdivan and Wm J Bruchey) tells us.

At a range of 50m, the 7.62x39 M67 offers slightly better terminal performance than the 5.56x45 M855A1.

However, at 300m, the 5.56x45 M855A1 becomes the superior of the two.




*BC of the 5.56x45 M855A1 was assumed to be 0.291
*BC of the 7.62x39 M67 was assumed to be 0.225

 

[BreechFace]

@481 So M855A1 gains another 100fps over M855? Most M855, 62gr hovers right at 3,000fps from a 16" barrel, from a 20" barrel one sees 3,100. Just my experiences and research.

I have no experience with M855A1, so if they got another 100fps that's a definite step up from the M855 along with the projectile benefits.

I know it's not a huge deal, but it's good to keep things consistent.

 

[valnar]

I assume those P[I/H] & T[I/H] figures change when barriers are introduced? I don't necessarily mean a car door or wall, but heavy clothing too.

I'm not discounting the capabilities of 5.56, but anecdotal evidence of some Vietnam vets (including at least one on this forum) are the 7.62x39 was pretty devastating.

 

[C-grunt]

M16

@481 So M855A1 gains another 100fps over M855? Most M855, 62gr hovers right at 3,000fps from a 16" barrel, from a 20" barrel one sees 3,100. Just my experiences and research.

I have no experience with M855A1, so if they got another 100fps that's a definite step up from the M855 along with the projectile benefits.

I know it's not a huge deal, but it's good to keep things consistent.

From what Ive seen current production M855A1 averages about 3125 FPS in a 20 inch barrel and 2950 FPS in a 14.5 inch barrel. I'd guess you would hit around 3000 FPS in a 16 inch barrel. In testing it was hotter and was causing premature wear on the rifle, but it seems like they tamed it down a bit for full release.

M855A1 is not a FMJ though. From what Ive heard from buddies that are still in or recently got out of the Army, it works really well.

 

[481]

@481 So M855A1 gains another 100fps over M855? Most M855, 62gr hovers right at 3,000fps from a 16" barrel, from a 20" barrel one sees 3,100. Just my experiences and research.

I have no experience with M855A1, so if they got another 100fps that's a definite step up from the M855 along with the projectile benefits.

I know it's not a huge deal, but it's good to keep things consistent.

Yes. The latest M855A1 has a higher muzzle velocity than earlier M855.

 

[shoobe01]

Skimming the 7 pages only: still gonna rag on the "FMJ" bit. You can buy: More than one type of ammo!

I (mostly) shoot 5.56 from self loading rifles, and I have and shoot mostly 62 gr ball. Not steel cored, lead ball. Cheap enough, safe for all targets. I also have (strewn about the house, always 1-2 in the bag, all marked with red tape and sharpie) some 64 gr Gold Dot. WAY more accurate, barrier blind, etc etc. But ballistically identical (yes, I checked) so if random baddies appear, I put in the social ammo.

There are several other options. Great things have been done with bullet design for terminal ballistics in the last 20 years or so. Such that you can even get good performing 5.56 terminal ballistics out of shorter barrels. Just buy suitable ammo (topped with a suitable bullet). And if you really think people may be an issue, they hide behind stuff, wear clothes, are in vehicles or structures, wear body armor, etc. Ball is... not especially effective. Yes, even plain old M80 ball or soft points from your .308 are not especially effective or deadly on people through barriers and armor.

Which leads to the key issue with 7.62 M43 (7.62x39): It is old. It is not in front line service. Even the snazziest Russian ammo (9x39) of which they make several variations, is several generations behind the top tier of the US for bullet design. And they don't do that work for .30 caliber bullets, no one does anything I am aware of that's too exciting in the .311 range in the US either. 7.62 MSC (mild steel core) is very old tech, and unlike M173 doesn't even accidentally give especially good terminal performance.

Oh, and also the flatter shooting 5.56 makes rangefinding less important so even out to 300 yds, you can much more easily set the gun up for aim-and-fire but you will have mediocre shot placement unless you account for drop with the 7.62 cartridge. You might not miss, but shot placement is important, isn't it?

So, the choice is a current issue cartridge by police, paramilitary, and militaries, or a legacy design firing ammo of decades old design.