Relevance of intermediate rounds such as 6.8 under 'new' paradigm?

[Jack-O]

As the kind Doc states, there have been a whole host of improvements in weapons and ballistics. The last 10 years particularly have pushed us forward farther and faster than the previous 20 IMO. No currently used rifle is what it was ten years ago. There have been major steps in weapon/ballistic advances made after the ban expired and 9-11-2001.

Like it or not, the civilian world often leads the military in technology. weapon systems are no different especially now we are in the information age. It’s basically like we operate in a huge testing lab where testing and results can be made available to anyone in a very short time. Doc Roberts has been and remains an important grounding element in ballistic research in what would otherwise be ruled by the guy with an attractive claim, a lot of spare time, a youtube video, and a high post count.

some earnest research on new platforms and available projectiles will reveal a great deal to one who seeks true knowledge.

if I havent said it recently… Thanks Doc for your, patient, candid and scientifically grounded responses to our questions.

jack

[lamarbrog]

@SHIVAN

Then you’d be well served to re-examine your desire to post here. You asked, he answered, and now you are still disagreeing with him. Worse still, you are doing so in a flippant manner, which I view as disrespectful.

This is a bad idea.

It is entirely possible to carry on this conversation with a far greater deference to knowledge, obviously outside your depth, being imparted.

Thanks.

I’m not sure what you mean by disrespectful. I am merely not in agreement with Dr. Roberts… I wasn’t aware that disagreement was not allowed.

If there is anything on this board I am qualified to comment on, it is terminal ballistics. While I have not had the time to amass the same credentials as Dr. Fackler or Dr. Roberts, for my age I think you will find I am very densely credentialed in the this field.

There are four people as far as the firearms/ammunition community goes that I would be absolutely honored to meet. Dr. Roberts is one of them. I have a habit, which some may say is a bad one, of being very plain and simply stating things as I see them.

I yield to Dr. Roberts’ wisdom in this area. I am not in total agreement… but I will argue no further, and will examine the resources I have at my disposal again.

Thank you.

[DocGKR]

lamarbrog–of course well reasoned disagreement is allowed! How else can we learn from one another and advance knowledge. Please keep posting and inquiring–I’ll do my best to provide additional information. More to follow.

[tpd223]

@Microalign

Dr. Fackler proved that the 7.62x39 was a poor performer in the M43 FMJ format:
http://www.uthr.org/SpecialReports/Martin%20Fackler,%20Stockton%20case.txt

The great thing about the 10% gel test is that we can measure the performance of projectiles in a medium that very closely resembles the hydrolic content of human tissue. 7.62x39mm projectiles in the Hornday AMAX, or other well engineered expansion loads perform quite well in 10% gel tests. Thus, the 7.62x39 is a great cartridge when decent ammunition is used.

I have attended autopsies of murder victims where non-Russian 7.62X39 ammo was used, and particularly with the noted Hornady load the wounding is nothing like that of a pistol round.

[dpaqu]

Is there a confirmed verdict on the “temporal stretch” vs wound channel/fragment argument?

[calvin118]

Thanks everyone for the great responses. Below is a comparison of the best performing barrier blind 5.56 round that I could find with the best performing 6.8 round that I could find from Doc’s data on this site:

5.56 mm Fed 62 gr FBI TBBC JSP (XM556FBIT3):
BG: Pen = 16.5", NL = 1.5cm, Max TC 11.5 cm @ 9 cm pen/extending to 17 cm, RD = 0.46", RL = 0.32", RW = 56.6 gr

6.8 mm Hornady 110 gr VMAX PT:
BG: 13.8", NL=0.5cm, Max TC=15cm@12cm from 0.5-20cm; RD=0.54”, RL=0.22”, RW=55.5gr

Clearly, the RD of the 6.8 projectile is larger, as is the TC. The question, as always in life, is whether the benefits outweigh the cost.

When considering 5.56 OTM rounds that fail to upset beyond ~50 yards out of a SBR and fail to defeat common barriers, I feel that a stronger case can be made that the benefits of the 6.8 outweigh the cost.

If the most significant advantage of the best 6.8 rounds over the best 5.56 is 3.5 cm of additional TC and .09" additional RD, it is harder for me to justify the cost of an identical upper (probably $1500 after optics, muzzle devices, bcg, etc.) and practice ammo. (It is nearly $1 per round, and even if I primarily practice with 5.56 there is going to be some felt difference and I am going to want to shoot the 6.8 sometimes as well).

As Doc has mentioned in other threads, quality barrier blind rounds have performed well in OIS incidents. The FBI has also selected a barrier blind 5.56 round, whereas they adopted the .40 after having problems with smaller calibers. This tells me that these rounds will do their job, even if the 6.8 does offer a small advantage around the margins of shot placement.

Is there a confirmed verdict on the “temporal stretch” vs wound channel/fragment argument?

Temporary cavity wounds fluid filled and inelastic organs such as the heart, brain, liver, spleen, kidneys, spinal cord, etc. It has minimal effect on muscle, lung parenchyma, and elastic connective tissue such as blood vessels. Fragmenting rounds do have an advantage because the fragments can act synergistically with the temporary cavity to damage tissues not inherently prone to being damaged by temporary cavitation. The head, central thorax, and abdomen, however, are rich with highly vascular structures prone to being damaged by temporary cavitation. With fair shot placement, I would expect hostilities to cease regardless of whether or not the round fragments so long as it upsets early and creates TC.

[lamarbrog]

@calvin118

Thanks everyone for the great responses. Below is a comparison of the best performing barrier blind 5.56 round that I could find with the best performing 6.8 round that I could find from Doc’s data on this site:

5.56 mm Fed 62 gr FBI TBBC JSP (XM556FBIT3):
BG: Pen = 16.5", NL = 1.5cm, Max TC 11.5 cm @ 9 cm pen/extending to 17 cm, RD = 0.46", RL = 0.32", RW = 56.6 gr

6.8 mm Hornady 110 gr VMAX PT:
BG: 13.8", NL=0.5cm, Max TC=15cm@12cm from 0.5-20cm; RD=0.54”, RL=0.22”, RW=55.5gr

Clearly, the RD of the 6.8 projectile is larger, as is the TC. The question, as always in life, is whether the benefits outweigh the cost.

When considering 5.56 OTM rounds that fail to upset beyond ~50 yards out of a SBR and fail to defeat common barriers, I feel that a stronger case can be made that the benefits of the 6.8 outweigh the cost.

If the most significant advantage of the best 6.8 rounds over the best 5.56 is 3.5 cm of additional TC and .09" additional RD, it is harder for me to justify the cost of an identical upper (probably $1500 after optics, muzzle devices, bcg, etc.) and practice ammo. (It is nearly $1 per round, and even if I primarily practice with 5.56 there is going to be some felt difference and I am going to want to shoot the 6.8 sometimes as well).

As Doc has mentioned in other threads, quality barrier blind rounds have performed well in OIS incidents. The FBI has also selected a barrier blind 5.56 round, whereas they adopted the .40 after having problems with smaller calibers. This tells me that these rounds will do their job, even if the 6.8 does offer a small advantage around the margins of shot placement.

Temporary cavity wounds fluid filled and inelastic organs such as the heart, brain, liver, spleen, kidneys, spinal cord, etc. It has minimal effect on muscle, lung parenchyma, and elastic connective tissue such as blood vessels. Fragmenting rounds do have an advantage because the fragments can act synergistically with the temporary cavity to damage tissues not inherently prone to being damaged by temporary cavitation. The head, central thorax, and abdomen, however, are rich with highly vascular structures prone to being damaged by temporary cavitation. With fair shot placement, I would expect hostilities to cease regardless of whether or not the round fragments so long as it upsets early and creates TC.

Of those things you listed as being damaged by temporary cavitation, many are not of great importance for immediate survival. Destroying your opponent’s liver is quite probably going to be fatal… but not immediately.

Suffocation through blood loss and damage to the central nervous system are the crucial factors here. CNS damage is largely just luck of the draw. If you get a spine shot, congratulations… I’m not counting on it, though.

That leaves suffocation through loss of blood. Since blood vessels are not readily damaged by temporary cavitation, maximum fragmentation is important because it allows a greater opportunity to strike a blood vessel.

[Jack-O]

Perhaps it would be easier for you to justify a switch to 6.8 if you looked at in a larger scope.

In your arsenal I’ll bet you have various level and power ranges of weapons. Answer for yourself the following question:

"If I could find one caliber that could take the place of TWO that I currently use, would it be worth it to me?

Right now the paradigm is that we have four or more ranges that weapons cover:
-Handgun (9, 40, 45) 0-50
-Assault rifle (223, 762x39, 545x39) 0-300
-Battle rifle (308, 30-06) 50-600
-Sniper rifle (300, 338) 100-1500+
-Anti-materiel (50)

What would it be like to combine the Assault and Battle rifles categories into one system and caliber. you might lose a little on the upper end, but you’d gain on the lower end where most stuff happens anyway.

Two guys. One is a close freind and the other just some guy on the internet. Internet guy shoots hogs for a living. tests out calibers and loads on REAL FLESH all the time. Claims that the 6.8 made a SIGNIFICANT difference over 223 regardless of bullet used, in how well the AR killed hogs. has HUNDREDS of kills a year. A LOT of hunters are discovering that the 6.8 has a lot of merit and it’s gaining a lot of popularity in that circle.

Other friend has several human kills under his belt using good ol M16a2’s and M855. Claims he never had any issues with the bullet or their ability to kill, and TO THIS DAY stands by the system and the bullets available with most of his “war” being the M855. Has NO INTENTION of switching to anything different either. And thats from a guy who tries out and learns new stuff all the time!

Heres the rub. Both are correct and have excellent reasons for using what they do. IMO it’s always gonna be the shooter first over the ballistics. in fact the ballistics pretty much come LAST in the progression of things you need when killing stuff.

If I were starting from scratch and buying a new platform and any caliber I wanted, then maybe I’d go with one of the super new gen carbines and the 6.8 instead of two whole guns and two calibers. I mean, if you are gonna learn something why not start out with something new right? problem is, most folks are not in that boat, so the decision is much more difficult and getting rid of the 223 and 308 is just not an option for them.

the 6.8 has a lot to offer, but only YOU will be able to determine whether it’s “worth it”

[calvin118]

@Jack-O

Perhaps it would be easier for you to justify a switch to 6.8 if you looked at in a larger scope.

In your arsenal I’ll bet you have various level and power ranges of weapons. Answer for yourself the following question:

"If I could find one caliber that could take the place of TWO that I currently use, would it be worth it to me?

Right now the paradigm is that we have four or more ranges that weapons cover:
-Handgun (9, 40, 45) 0-50
-Assault rifle (223, 762x39, 545x39) 0-300
-Battle rifle (308, 30-06) 50-600
-Sniper rifle (300, 338) 100-1500+
-Anti-materiel (50)

What would it be like to combine the Assault and Battle rifles categories into one system and caliber. you might lose a little on the upper end, but you’d gain on the lower end where most stuff happens anyway.

Two guys. One is a close freind and the other just some guy on the internet. Internet guy shoots hogs for a living. tests out calibers and loads on REAL FLESH all the time. Claims that the 6.8 made a SIGNIFICANT difference over 223 regardless of bullet used, in how well the AR killed hogs. has HUNDREDS of kills a year. A LOT of hunters are discovering that the 6.8 has a lot of merit and it’s gaining a lot of popularity in that circle.

Other friend has several human kills under his belt using good ol M16a2’s and M855. Claims he never had any issues with the bullet or their ability to kill, and TO THIS DAY stands by the system and the bullets available with most of his “war” being the M855. Has NO INTENTION of switching to anything different either. And thats from a guy who tries out and learns new stuff all the time!

Heres the rub. Both are correct and have excellent reasons for using what they do. IMO it’s always gonna be the shooter first over the ballistics. in fact the ballistics pretty much come LAST in the progression of things you need when killing stuff.

If I were starting from scratch and buying a new platform and any caliber I wanted, then maybe I’d go with one of the super new gen carbines and the 6.8 instead of two whole guns and two calibers. I mean, if you are gonna learn something why not start out with something new right? problem is, most folks are not in that boat, so the decision is much more difficult and getting rid of the 223 and 308 is just not an option for them.

the 6.8 has a lot to offer, but only YOU will be able to determine whether it’s “worth it”

I agree with you just about right down the line. If I was starting fresh and practice ammo was reasonably priced, I think the 6.8 would be a more logical choice than 5.56. Given what most of us already have invested in 5.56 carbines coupled with the price of magazines and practice ammo in 6.8, it does not seem worth it to me at this point. Before I became aware of barrier blind 5.56 rounds that worked well out to 300 yards, the gap seemed larger and the 6.8 looked a lot more attractive.

I have heard the same thing from hunters, but keep in mind bipedal thin-skinned human have a lot less in the way of vitals than hogs. If I was going hog hunting, a 6.8 upper would once again be high on my list.

Everyone I know who has used the 5.56 in combat tells me it works fine as well.

[calvin118]

@lamarbrog

Of those things you listed as being damaged by temporary cavitation, many are not of great importance for immediate survival. Destroying your opponent’s liver is quite probably going to be fatal… but not immediately.

Suffocation through blood loss and damage to the central nervous system are the crucial factors here. CNS damage is largely just luck of the draw. If you get a spine shot, congratulations… I’m not counting on it, though.

That leaves suffocation through loss of blood. Since blood vessels are not readily damaged by temporary cavitation, maximum fragmentation is important because it allows a greater opportunity to strike a blood vessel.

The liver, spleen, kidneys, etc. are vascular organs that accept a high percentage of cardiac output relative to their mass. I have seen plenty of blunt liver trauma (which is analogous to the injury caused by TC) and it can be disastrous. A temporary cavity tearing through the liver would cause rapid hemorrhage and incapacitation; it is definitely not an organ you want injured.

[vicious_cb]

@Jack-O

Perhaps it would be easier for you to justify a switch to 6.8 if you looked at in a larger scope.

In your arsenal I’ll bet you have various level and power ranges of weapons. Answer for yourself the following question:

"If I could find one caliber that could take the place of TWO that I currently use, would it be worth it to me?

Right now the paradigm is that we have four or more ranges that weapons cover:
-Handgun (9, 40, 45) 0-50
-Assault rifle (223, 762x39, 545x39) 0-300
-Battle rifle (308, 30-06) 50-600
-Sniper rifle (300, 338) 100-1500+
-Anti-materiel (50)

What would it be like to combine the Assault and Battle rifles categories into one system and caliber. you might lose a little on the upper end, but you’d gain on the lower end where most stuff happens anyway.

Things aren’t as cut and dry as that, not to mention its the skill of the shooter that will determine the effective range of a weapon/caliber system. I bet there are guys here or know of guys who have slain past 600m with 5.56. As for replacing 2 calibers, if you look at the BCs of 6.8 match loads, they aren’t much better than 5.56 match loads.

[Jack-O]

@vicious_cb

Things aren’t as cut and dry as that, not to mention its the skill of the shooter that will determine the effective range of a weapon/caliber system. I bet there are guys here or know of guys who have slain past 600m with 5.56. As for replacing 2 calibers, if you look at the BCs of 6.8 match loads, they aren’t much better than 5.56 match loads.

you should read the rest of my post where I say as much.

That handy “rule” is packaged for easy consumption. Hell, even math has exceptions to rules.

[Swatdude1]

@vicious_cb

Things aren’t as cut and dry as that, not to mention its the skill of the shooter that will determine the effective range of a weapon/caliber system. I bet there are guys here or know of guys who have slain past 600m with 5.56. As for replacing 2 calibers, if you look at the BCs of 6.8 match loads, they aren’t much better than 5.56 match loads.

I think the point you guys are missing is that for those match loads you speak of, the cost of the ammo is the same. Actually, when comparing the 5.56 Black Hills 50gr TSX, the Hornady 6.8 110 BTHP is significantly less money. Doc can comment on which is the better performing round. This influenced me to go ahead and invest in the price of admission for 6.8. When training, I find the difference in recoil in the AR platform a non-issue on accuracy and so the cheap 5.56 ammo is a viable alternative for use as a practice round. The XM193 actually has more recoil than alot of the other rounds I have shot including the weaker 75gr TAP FPD. Unless you are training monthly (I wish) for your job or you have unlimited time and cash, swapping optics and light mounts from the 5.56 to 6.8 is a non-issue, so you really should just be considering the cost of the upper and mags.

I really enjoy my MSAR E4 for this reason. I purchased a 6.8 kit from Ratworx and all that is required is a bolt and EASY barrel swap (AUG platform). Optics and light stays in place. With a few clicks on the Trijicon and I’m gtg.

[WS6]

I think the main problem is that a while back (“while back” as used in man-terms, like “The other day…”) the military was ONLY fielding FMJ ammunition, and the only other ammunition available in .223 was of the varmint variety, or fragmenting JSP’s (JSP’s that “failed”, etc.)

The 7.62x39 was only readily available in FMJ.

6mm, 7mm, .308, .30-06 etc. were only available in heavier rifles, or rifles like the HK-91, etc. They didn’t see a whole ton of use in killing people except in FMJ. Everyone agreed that .30-06 in FMJ > 5.56 FMJ. However, the neighbor family 10 houses down that you like hanging out with would ALSO agree that your M1A>AR-15…

Well, now things are different. Ammunition performance has been tuned in such a way that construction and material allow the penetration to be controlled through either expansion, fragmentation, or both.

Now, mass and kinetic energy are king, because bullet construction takes care of over-penetration and terminal performance.

The crux of the matter has become…Can I accurately control a light weapon shooting projectiles of this weight rapidly? and then picking the platform that launches the biggest projectile with the highest KE that you can rapidly and effectively shoot that is available in the platform of your choosing/has the features you need to run it effectively.

Then you select a projectile that has maximum upset and penetrates between 12-16".

The 5.56 is very controllable, but not much is given up by going to 6.8, etc.

Summation:
It’s no-longer a question of cartridge characteristic. It’s a question of platform characteristic, because it has become about maximum mass and KE vs. controllability while the projectile manufacturers have taken care of the rest by giving us projectiles tuned to the task across the caliber and velocity spectrum.

Just my take on it.

[WS6]

@calvin118

I agree with you just about right down the line. If I was starting fresh and practice ammo was reasonably priced, I think the 6.8 would be a more logical choice than 5.56. Given what most of us already have invested in 5.56 carbines coupled with the price of magazines and practice ammo in 6.8, it does not seem worth it to me at this point. Before I became aware of barrier blind 5.56 rounds that worked well out to 300 yards, the gap seemed larger and the 6.8 looked a lot more attractive.

I have heard the same thing from hunters, but keep in mind bipedal thin-skinned human have a lot less in the way of vitals than hogs. If I was going hog hunting, a 6.8 upper would once again be high on my list.

Everyone I know who has used the 5.56 in combat tells me it works fine as well.

As another data-point, I have heard the same. My former roommate used the 5.56 in the guise of M855 to kill people. We didn’t discuss it in detail as he’s not someone who glorifies what he did or wishes to reminisce about killing people, but he simply said “If you put it COM where it belongs, it did it’s job quickly and decisively. I only used it out to about 120 yards or so. Most of our combat was closer in.”

He was in Iraq for a few years back in the early 2000’s.

@SHIVAN

Then you’d be well served to re-examine your desire to post here. You asked, he answered, and now you are still disagreeing with him. Worse still, you are doing so in a flippant manner, which I view as disrespectful.

This is a bad idea.

It is entirely possible to carry on this conversation with a far greater deference to knowledge, obviously outside your depth, being imparted.

Thanks.

@DocGKR

lamarbrog–of course well reasoned disagreement is allowed! How else can we learn from one another and advance knowledge. Please keep posting and inquiring–I’ll do my best to provide additional information. More to follow.

+1. I have disagreed with you on several occasions. I have a medical degree, but am not an MD, nor have I seen anyone shot personally besides a friend who was cleaning his G32, but that’s another story. Dr. Roberts politely and professionally has disagreed with me, supported his stance, and changed my opinion on a number of things after I saw his side of the story. I never once found him to be “above” polite debate with me, nor did he ever “talk down” to me from his educational or professional position. If people DO NOT post their disagreement with him, they are missing out. I learned more from people by disagreeing with them than agreeing. The “trick” is to remain open-minded to THEIR side of the debate, engage respectfully, and focus on LEARNING more than “WINNING”.

I have found Dr. Roberts to be one of the most “accessible” and polite MD’s I have spoken to. That includes the ones I work with. He is a valuable asset to the community, and I don’t say this to suck up, I say this because you don’t HAVE TO suck up to the guy, and you CAN get cross-wise with him a full 90* on a topic and as long as you are polite, he will engage you intelligently on the issue and you have a wonderful opportunity to learn things. I cannot recall a single time where he has said anything analogous to “Because I said so, and here is my resume”. No. He point-by-point explains things in layman’s terms, or as technically detailed as you would like. Or directs you to where it has been done 1,000 times over if you ask something ridiculous.

Lets not relegate him to an ivory tower or canonize his words. The guy is a great teacher and it would seriously hamper our ability to learn anything from him. If someone still truly disagrees after Dr. Roberts has said his piece on the matter, why begrudge them that? As long as Dr. Roberts is responding, he has something to say. He doesn’t need “protection” from the questions of others.

I do fully agree that he deserves the same respect that others deserve–to be engaged politely and respectfully, as he has done so with those who engage him.

I have found that to be true of any MD I have spoken to. I call and wake MD’s up all night long at work, and have yet to be lambasted or treated ill for it. I simply speak respectfully, and accept nothing short in return. It has worked well.

[SHIVAN]

@WS6

Lets not relegate him to an ivory tower or canonize his words. The guy is a great teacher and it would seriously hamper our ability to learn anything from him. If someone still truly disagrees after Dr. Roberts has said his piece on the matter, why begrudge them that? As long as MD Roberts is responding, he has something to say. He doesn’t need “protection” from the questions of others.

It was not the question from which he was being “protected”. Just remember that not everyone’s perspective is the same during their participation on this forum. Staff and Mods see things a little differently, based on our roles for site participation.

The words written indicated that lamarbrog obviously considered himself a peer of Dr. Roberts, and then closed his disagreement with “And, before you say something, yes, I know who you are.”

This sounded flippant, and dismissive. Which might work Ok for others, except that his comment was directed towards a respected Industry Professional. Until further clarification was made, this is a no-go on this site.

Now that I have clarification, and Doc has voiced his consent to furthering the discussion, it appears benign. At the time, it looked like it was going to be an issue that needed handling.

Again, this is about perspective, mods and staff are required to look towards maintaining some semblance of order, and that looked like a sure derailment in the making.

I do fully agree that he deserves the same respect that others deserve–to be engaged politely and respectfully, as he has done so with those who engage him.

Actually, his work, and his identification as an IP, afford him an elevated level of respect. We’re not trying to fool ourselves on M4Carbine into believing that all opinions are equal, they’re not.

You are 100% correct though, his IP status and work does not set him above rational, and respectful, disagreement. I just wasn’t sure that was the road on which lamarbrog was headed.

Thanks for taking the time to respond, but it would appear this particular issue has been ironed out, and we can return to our regularly scheduled programming.

[WS6]

@SHIVAN

It was not the question from which he was being “protected”. Just remember that not everyone’s perspective is the same during their participation on this forum. Staff and Mods see things a little differently, based on our roles for site participation.

The words written indicated that lamarbrog obviously considered himself a peer of Dr. Roberts, and then closed his disagreement with “And, before you say something, yes, I know who you are.”

This sounded flippant, and dismissive. Which might work Ok for others, except that his comment was directed towards a respected Industry Professional. Until further clarification was made, this is a no-go on this site.

Now that I have clarification, and Doc has voiced his consent to furthering the discussion, it appears benign. At the time, it looked like it was going to be an issue that needed handling.

Again, this is about perspective, mods and staff are required to look towards maintaining some semblance of order, and that looked like a sure derailment in the making.

Understood. I took his comment to mean “I know who you are, I know you know a lot of things, I still disagree with you, regardless, and require clarification if I am to change my opinion.”

However, you look at things differently because it’s your “job”, and I understand that. Just like as a shopper, I wonder if someone has something dangerous to me in their heavy coat in the summer in wal-mart. The store manager is worried about his electronics displays, and the coat-wearer feels alienated because their chemo treatments leave them easily chilled and everyone is looking at them funny.

Actually, his work, and his identification as an IP, afford him an elevated level of respect. We’re not trying to fool ourselves on M4Carbine into believing that all opinions are equal, they’re not.

His position deserves more respect because there is more knowledge and experience behind it, and his opinion should carry more weight because of that, but I feel that every human being who does their job, supports society, and respects others deserves to be treated as we ourselves want to be treated. Black, white, rich, poor, MD, GED.

You are 100% correct though, his IP status and work does not set him above rational, and respectful, disagreement. I just wasn’t sure that was the road on which lamarbrog was headed.

Thanks for taking the time to respond, but it would appear this particular issue has been ironed out, and we can return to our regularly scheduled programming.

Agreed. I have just seen so many times where an “industry professional” is placed on a pedestal as “beyond question” and it irks me. I am happy to see that Dr. Roberts is not of that ilk.

I am interested in what appears to be a “change mid-stream” as to Dr. Roberts views on 5.56 ammunition. I understand that it is due to new technology in projectile design being applied. However, it is interesting to me that he has changed his stance after preaching “Heavy OTM except through glass” for so long. It’s refreshing to see someone “important” change their tune to support new data without fearing that it will erode their status.

People rarely use the sea-green.

[Arctic1]

@lamarbrog

Of those things you listed as being damaged by temporary cavitation, many are not of great importance for immediate survival. Destroying your opponent’s liver is quite probably going to be fatal… but not immediately.

Suffocation through blood loss and damage to the central nervous system are the crucial factors here. CNS damage is largely just luck of the draw. If you get a spine shot, congratulations… I’m not counting on it, though.

That leaves suffocation through loss of blood. Since blood vessels are not readily damaged by temporary cavitation, maximum fragmentation is important because it allows a greater opportunity to strike a blood vessel.

With all due respect, suffocation (asphyxiation) is not an incapacitation mechanism from a gun shot wound.

The major complication from massive blood loss is hypovolemic shock, resulting in inadequate peripheral perfusion of the tissues, which eventually causes circulatory collapse due to major organ failure throughout the body, resulting in death.

It the liver, spleen and kidneys are damaged, the likelihood of additional damage is present, and will contribute to reducing the effects of the bodies cardiovascular responses to the trauma sustained.

[lamarbrog]

@Arctic1

With all due respect, suffocation (asphyxiation) is not an incapacitation mechanism from a gun shot wound.

The major complication from massive blood loss is hypovolemic shock, resulting in inadequate peripheral perfusion of the tissues, which eventually causes circulatory collapse due to major organ failure throughout the body, resulting in death.

It the liver, spleen and kidneys are damaged, the likelihood of additional damage is present, and will contribute to reducing the effects of the bodies cardiovascular responses to the trauma sustained.

My apologies. I was somewhat distracted when I wrote that. I was going for “exsanguination”, but instead went with the colloquial form of “asphyxiation”. Anyway, blood loss.

As you say, I’m not quite sure how someone would suffocate as a result of a gunshot wound.

[Moltke]

In response to the OP’s question - “is there much of a point to larger calibers such as the 6.8 anymore?”

Yes.

Wounding comes from penetration, permanent cavity, temporary cavity, and fragmentation right? Right. So the bigger the bullet, the more mass, more diameter, more expansion or more fragmentation you’re going to achieve. Unlike the small differences between 9mm, 40sw & 45acp wounding capabilities, the differences between rifle wound tracks are quite significant as you can see from Doc’s posted pics. Anything a 5.56mm can do, a 6.8mm or 7.62mm can do better and the difference is not marginal. Scaling up a load from 5.56mm to a 6.8mm or 7.62mm means that you’ll get a lot more fragmentation or controlled expansion, along with a lot more temporary cavity. No matter what you’re shooting from dogs, hogs, people or large game, the larger bullet of similar design is always going to have a larger and more horrendous wound track.