Green Tipped 5.56 NATO Vs. 5.56 55gr

[DustyGmt]

In my opinion, the M193 is the better round overall, but I keep plenty of M855 on hand for SBR's. Lower velocity due to barrel length and the specific projectile make penetration far better than M193 from a SBR.

Hmm. Never really gave it any thought. I imagine in a military context it would certainly be advantageous.....

 

[12Bravo20]

In my opinion, the M193 is the better round overall, but I keep plenty of M855 on hand for SBR's. Lower velocity due to barrel length and the specific projectile make penetration far better than M193 from a SBR.

The US Military saw a need to improve the round for use in the 14.5" barreled M4 Carbines. That is why the M855A1 was developed. The M855A1 doe a better job out of sub 16" barrels versus the M855.

 

[TGW1979]

I hear you neighbor, (Vermont). But lately it's been too damn cold and blustery to do any prolonged shooting, although last week was a very good week for me shooting wise, I went out and shot for a couple hours a day 5 out of 7 days......

Oh I know. I'm right here in the middle of New Hampshire and I want to take my AR-15 out.. I need to cite it in. But I'd like to do that at 100 yards and first of all there's no good places around here that are easily accessible with this amount of snow where I can get a 100 yd shot off. And any other place I'm going to be trudging through snow off into the woods locally and yeah I don't want to shoot paper targets at 50 ft with an ar-15. Seems like a waste of ammo to me.

 

[lysanderxiii]

The US Military saw a need to improve the round for use in the 14.5" barreled M4 Carbines. That is why the M855A1 was developed. The M855A1 doe a better job out of sub 16" barrels versus the M855.

The main driver for M855A1 was to make a lead free projectile.

 

[12Bravo20]

The main driver for M855A1 was to make a lead free projectile.

Yet it was also developed to get better performance out of the 10.5" and 14.5" barrels too.

 

[redcon1]

Yet it was also developed to get better performance out of the 10.5" and 14.5" barrels too.

The M855's inconsistent terminal effects were increasingly evident in carbine length rifles going back to our experience in Mogadishu (Blackhawk Down) where the SS109 projectile failed to put down Somalians despite multiple COM hits. It exhibited a number of inconsistent terminal effects in Iraq. The Army determined that the M855 wasn't consistently yawing/pitching/tumbling/fragmenting terminally and was, instead, ice picking through targets, especially evident in skinny malnourished Afghani/ jihadi/somali types. The inconsistencies were related to velocity and impact angle and was called "fleet yaw".

This ultimately led to the use of the Mk262 and Mk 318 rounds and then the development of M855A1 EPR.

The M855A1 is literally called the "M855A1 EPR"-Enhanced Performance Round. The big performance enhancement is that it exhibits more consistent yawing effects regardless of the striking angle, better barrier penetration and optimization for shorter barreled weapons which are more favored than a full sized rifle in Military Operations in Urban Terrain and Close Quarters Battle. It also happens to be environmentally friendly which was another feature of the bullet that was designed in parallel with its enhanced performance.

Also worth mentioning that sometimes the greentip is devastatingly effective and sometimes it isn't and this is due to this fleet yaw effect which is observed in the following photograph. Yawing is dependent on impact angle. Yawing is what leads to the bullet fragmenting in the target. Yawing is therefore extremely important and, as such, we have to wonder what mechanisms lead to inconsistent yawing in the M855/SS109. Is it velocity? Stability? Is a more stable bullet actually less lethal? Probably so. So, at what ranges is the bullet most stable? Least stable? On the other hand if you're shooting at armor, you probably want that SS109 to hit dead on and there's probably a range where that is most likely to occur and that desired stability is going to be related to velocity and, thus barrel length. But, if you're shooting at soft targets in the open, you want that bullet to hit at a higher angle to induce terminal yaw effects and there's probably a range/velocity where that instability is most likely to happen. The M855A1 round made all of this less of a consideration.

 

[cowboy77845]

We shot some 62 gr. green tip in my Weatherby Vanguard while zeroing with various 55 gr. loads. It never hit the paper. It shot minute of a pie plate in my mini-14. Now I have all this green tip and it will not group in my rifles.

 

[lysanderxiii]

The M855's inconsistent terminal effects were increasingly evident in carbine length rifles going back to our experience in Mogadishu (Blackhawk Down) where the SS109 projectile failed to put down Somalians despite multiple COM hits. It exhibited a number of inconsistent terminal effects in Iraq. The Army determined that the M855 wasn't consistently yawing/pitching/tumbling/fragmenting terminally and was, instead, ice picking through targets, especially evident in skinny malnourished Afghani/ jihadi/somali types. The inconsistencies were related to velocity and impact angle and was called "fleet yaw".

This ultimately led to the use of the Mk262 and Mk 318 rounds and then the development of M855A1 EPR.

The M855A1 is literally called the "M855A1 EPR"-Enhanced Performance Round. The big performance enhancement is that it exhibits more consistent yawing effects regardless of the striking angle, better barrier penetration and optimization for shorter barreled weapons which are more favored than a full sized rifle in Military Operations in Urban Terrain and Close Quarters Battle. It also happens to be environmentally friendly which was another feature of the bullet that was designed in parallel with its enhanced performance.

Also worth mentioning that sometimes the greentip is devastatingly effective and sometimes it isn't and this is due to this fleet yaw effect which is observed in the following photograph. Yawing is dependent on impact angle. Yawing is what leads to the bullet fragmenting in the target. Yawing is therefore extremely important and, as such, we have to wonder what mechanisms lead to inconsistent yawing in the M855/SS109. Is it velocity? Stability? Is a more stable bullet actually less lethal? Probably so. So, at what ranges is the bullet most stable? Least stable? On the other hand if you're shooting at armor, you probably want that SS109 to hit dead on and there's probably a range where that is most likely to occur and that desired stability is going to be related to velocity and, thus barrel length. But, if you're shooting at soft targets in the open, you want that bullet to hit at a higher angle to induce terminal yaw effects and there's probably a range/velocity where that instability is most likely to happen. The M855A1 round made all of this less of a consideration.
View attachment 1061383

M855 Yaw characteristics:





Compare to the yaw characteristics of the M193:


The M855 is ore dynamically stable, the yaw damps out as range increases. The M193 is dynamically neutral and maintains a fairly high yaw angle down range.

 

[herrwalther]

The main driver for M855A1 was to make a lead free projectile.

That was the main headline in rags like the Armytimes. Which put a left spin on anything DOD related. There was a lot more that went into the development of M855A1 than just wanting a lead-free projectile. This short article shows the difference slightly better than other publications I read.
https://www.military.com/equipment/m855a1-enhanced-performance-round

 

[redcon1]

The M855 is ore dynamically stable, the yaw damps out as range increases. The M193 is dynamically neutral and maintains a fairly high yaw angle down range.

It's hard to believe that the M855 is inherently more statically stable than the M193 given that the M193 is a simple lead jacketed projectile and the SS109 has the more complex construction of the steel penetrator which would increase the probability of having variations in the center of gravity and would lead to gyroscopic instability and lateral throw off and increased shot group dispersion, etc. This is why Paul Harrell sees better accuracy with the M193 round and he explains that at around 7:30 in his comparison of M193 and M855 youtube video. He is comparing these two rounds at 100 yards however. At 100 yards, the lighter M193 has the advantage and shoots better than the M855. At longer ranges, the heavier SS109 projectile with the better BC has the advantage over the lighter M193 projectile which should translate into better long range accuracy potential except we're talking about military ball ammo which is far from match grade so.

The 1:7 twist for the M855 is pretty tight too which would exacerbate any lateral throwoff issues. Given that the M16A2 was given a 1:7 twist to stabilize the longer M856 tracer round in arctic conditions, not the M855 ball round, the shorter ss109 green tip is actually over stabilized at 1:7 which, as noted, would lead to increased lateral throwoff and increased shotgroup dispersion. The actual required twist rate to stabilize the M855 SS109 is 1:10" so 1:7 seems like quite a bit more than what is required.

The M193 probably has the overall advantage IMO as it more reliably fragments at typical combat distances. The SS109 has the advantage in penetration of course but even that is not guaranteed as evidenced by observational experiences in Iraq where it failed to penetrate automobile windshields (but of course, there are plenty of reports of it going right through windshields just fine) and penetration is great for handgun bullets but for .223 rifle bullets, fragmentation is much more preferable.

But some, perhaps many, of us have thousands of these SS109 projectiles lying around so it's probably best to understand where and how they perform well and where and how they perform poorly. And, the bottom line is, for the most part, they kill enemy soldiers pretty darned good and the reports of their failure are exceptions, not necessarily the rule so, I maintain, shooting them into the dirtpile because they aren't M855A1 or M193 and someone on the internet said they weren't any good might not be the best idea. Maybe some of them but I'm not wasting mine.

 

[HowieG]

I was in a Bradley Fighting Vehicle. The shorter barrel kind of made sense in the back of a BFV and back then, I recall, the M4 was really starting to become more of status thing than a lethality thing IMO. They just looked cool and the cool kids had them and everybody wanted one and I guess they were probably newer and shinier than our well used A2s but even back then, I would have preferred a nice A2 with a 20" barrel over a nice M4 with a 14.5" barrel. I think that, after the lessons of Mogadishu, the United States DOD has probably wasted a lot of resources trying to squeeze 20" barrel terminal effects out of shorter than 20" barrels ultimately culminating in the M855A1 round which seems pretty potent, (perhaps too potent for the platforms that might fire it in fact) and again, are US threats going to be wearing AR500 plates? Russians? Chinese? Maybe. I don't know. Regardless, I think at close range in a 14.5" barrel, against unarmored threats, I'd want M193 and, honestly, I think the good old M193 round has its own armor defeating capabilities, especially when velocity is maximized. There's no rule that says you have to aim COM. The M855 is OK for what it is. It doesn't penetrate as well as the M855A1 which is not readily obtainable for most of us anyways (and it would probably wreck our guns if we used it routinely) and It doesn't fragment as well as the M193 55 grain cannelured projectile. because of its construction, it also isn't going to be as accurate as any commercial bullet or even the 55 grain bullet but it will hold its velocity longer and it's probably going to penetrate better than your typical commercial bullet or the 55 grain M193 projectile especially with max velocity.

Our fighting vehicle weapon was the M3 submachine gun, cal. 45 ACP. After I got out, I think they went for the XM177E2 for a little while.

 

[redcon1]

Our fighting vehicle weapon was the M3 submachine gun, cal. 45 ACP. After I got out, I think they went for the XM177E2 for a little while.

The dismounted infantry soldier in the back of a Bradley Fighting Vehicle was kind of an enigma. They were kind of armored but they were still technically infantry. Our role was to support and defend the armored vehicle primarily but, at the same time, we were expected to carry out traditional infantry operations and the BFV was expected to be an infantry weapon but, at the same time, we operated alongside tanks and trained to maneuver against and to destroy enemy tanks and vehicles and troops. So the role of those soldiers inside was complex but I feel like, given our infantry role, a full sized rifle made more sense even if it was harder to move around inside the vehicle with one. It wasn't that much harder. The beauty was, we could carry way more grenades, mines, rockets and ammunition into battle than a standard 11B on foot.

 

[HowieG]

The dismounted infantry soldier in the back of a Bradley Fighting Vehicle was kind of an enigma. They were kind of armored but they were still technically infantry. Our role was to support and defend the armored vehicle primarily but, at the same time, we were expected to carry out traditional infantry operations and the BFV was expected to be an infantry weapon but, at the same time, we operated alongside tanks and trained to maneuver against and to destroy enemy tanks and vehicles and troops. So the role of those soldiers inside was complex but I feel like, given our infantry role, a full sized rifle made more sense even if it was harder to move around inside the vehicle with one. It wasn't that much harder. The beauty was, we could carry way more grenades, mines, rockets and ammunition into battle than a standard 11B on foot.

If you are old enough, you may remember the firing port weapons that came with the early Brads? And the actual firing ports? What a joke! Just more crap to take care of.

 

[redcon1]

If you are old enough, you may remember the firing port weapons that came with the early Brads? And the actual firing ports? What a joke! Just more crap to take care of.

Right, we had a bunch of those in the arms room. We ultimately used them as trench clearing weapons as they were shorter and handier in the confines of a trench and they were full auto.

 

[HowieG]

Right, we had a bunch of those in the arms room. We ultimately used them as trench clearing weapons as they were shorter and handier in the confines of a trench and they were full auto.

That is really interesting. I would have thought that trench doctrine would be to stand off and give it a good dose of 25mm Bushmaster.

A really good movie for a Brad guy is Pentagon Wars with Cary Elwes if you haven't already seen it.

 

[redcon1]

That is really interesting. I would have thought that trench doctrine would be to stand off and give it a good dose of 25mm Bushmaster.

Sure, but trench entering/clearing is a standard infantry battle drill so we had to train for it to the standard which means organic weapons. I think our platoon and squad leaders were actually looking for some kind of use for the port firing weapons and the CO was amenable. It was an effective weapon for establishing a foothold after throwing your grenades and moving into the trench.

A really good movie for a Brad guy is Pentagon Wars with Cary Elwes if you haven't already seen it.

I saw it but it was a long time ago. The BFV was a nice tool to have but there was some confusion how best to use that tool. There's something to be said for having a bunch of 25mm chain guns backing up your attack.

 

[HowieG]

Sure, but trench entering/clearing is a standard infantry battle drill so we had to train for it to the standard which means organic weapons. I think our platoon and squad leaders were actually looking for some kind of use for the port firing weapons and the CO was amenable. It was an effective weapon for establishing a foothold after throwing your grenades and moving into the trench.

I saw it but it was a long time ago. The BFV was a nice tool to have but there was some confusion how best to use that tool. There's something to be said for having a bunch of 25mm chain guns backing up your attack.

I think the Brad got a little big and complex (both the M2 and M3). That being said, having TOW antitank capability certainly came in handy in the Gulf War, and the chain gun certainly worked really well in those big urban fights in Iraq.

 

[redcon1]

I think the Brad got a little big and complex (both the M2 and M3). That being said, having TOW antitank capability certainly came in handy in the Gulf War, and the chain gun certainly worked really well in those big urban fights in Iraq.

It's better to have a TOW missile and a 25mm chaingun and not need them than to need a TOW missile and a 25mm chaingun and not have them. I was fortunate and never needed either though I missed Iraq by about a month. I actually got orders to deploy but they cancelled them at the last minute so I was able to graduate on time.

 

[HowieG]

It's an interesting place in a Trumpian sort of way if you get my drift.

 

[redcon1]

It's an interesting place in a Trumpian sort of way if you get my drift.

Seems more Bushian to me.

 

[lysanderxiii]

It's hard to believe that the M855 is inherently more statically stable than the M193 given that the M193 is a simple lead jacketed projectile and the SS109 has the more complex construction of the steel penetrator which would increase the probability of having variations in the center of gravity and would lead to gyroscopic instability and lateral throw off and increased shot group dispersion, etc. This is why Paul Harrell sees better accuracy with the M193 round and he explains that at around 7:30 in his comparison of M193 and M855 youtube video. He is comparing these two rounds at 100 yards however. At 100 yards, the lighter M193 has the advantage and shoots better than the M855. At longer ranges, the heavier SS109 projectile with the better BC has the advantage over the lighter M193 projectile which should translate into better long range accuracy potential except we're talking about military ball ammo which is far from match grade so.

The 1:7 twist for the M855 is pretty tight too which would exacerbate any lateral throwoff issues. Given that the M16A2 was given a 1:7 twist to stabilize the longer M856 tracer round in arctic conditions, not the M855 ball round, the shorter ss109 green tip is actually over stabilized at 1:7 which, as noted, would lead to increased lateral throwoff and increased shotgroup dispersion. The actual required twist rate to stabilize the M855 SS109 is 1:10" so 1:7 seems like quite a bit more than what is required.

The M193 probably has the overall advantage IMO as it more reliably fragments at typical combat distances. The SS109 has the advantage in penetration of course but even that is not guaranteed as evidenced by observational experiences in Iraq where it failed to penetrate automobile windshields (but of course, there are plenty of reports of it going right through windshields just fine) and penetration is great for handgun bullets but for .223 rifle bullets, fragmentation is much more preferable.

But some, perhaps many, of us have thousands of these SS109 projectiles lying around so it's probably best to understand where and how they perform well and where and how they perform poorly. And, the bottom line is, for the most part, they kill enemy soldiers pretty darned good and the reports of their failure are exceptions, not necessarily the rule so, I maintain, shooting them into the dirtpile because they aren't M855A1 or M193 and someone on the internet said they weren't any good might not be the best idea. Maybe some of them but I'm not wasting mine.

Do not confuse a bullets inherent stability with its accuracy.

Stability is a measure of the behavior of the long axis of the bullet relative to the path of flight.

Accuracy is how well one path of flight matches the previous, and the next.

 

[HowieG]

Seems more Bushian to me.

I was referring to Trump's nickname for places like that.

 

[DustyGmt]

I was reading recently where a guy conducted some tests with the M855, M193 and M855A1 and surprisingly out of his 14.5" AR (presumably a colt) he shot a nice group of 10 M855 that measured just over an inch @ 100y Pretty crazy, the best I've gotten in a 16" with M855 is about minute of paper plate. Scattershot.

I never really cared for it, especially not enough to justify the $70-$120 per case price difference it's fluctuated back and fourth between over the years...

 

[redcon1]

I was referring to Trump's nickname for places like that.

Now it makes sense. LOL

 

[HowieG]

I was reading recently where a guy conducted some tests with the M855, M193 and M855A1 and surprisingly out of his 14.5" AR (presumably a colt) he shot a nice group of 10 M855 that measured just over an inch @ 100y Pretty crazy, the best I've gotten in a 16" with M855 is about minute of paper plate. Scattershot.

I never really cared for it, especially not enough to justify the $70-$120 per case price difference it's fluctuated back and fourth between over the years...

He was probably shooting at 25 meters.