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A McGowen AR 10 barrel in 270-08 18" 1:7 twist (1:7, 1:7.7 and many slower twists available) for the AR 10 with threaded barrel, semi-custom profile, etc prices out at $430. That's same twist as the SIG Fury so stabilizing military pulls when they begin to pop up (always do, just may have to pay) should be able to load them into an AR 10 and motor on!
 

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Seems like a lot of people agree with my assessment that the more ideal solution would have been to dump 5.56 in favor of 6.8 SPC (II) and field the 277 Sig Fury primarily for long range or DMR roles. The problem is, they are always looking for one size fits all solutions and that's simply not optimal for all situations.

I can guarantee you that at CQB distances a 6.8 upper would be notably faster for entry work than a MCX Spear equivalently equipped (optics, lights, IR) and notably less front heavy while delivery nearly the same terminal performance (as far as it matters). 6.8mm vs. 6.8mm, at close range there's not much advantage to the Fury, but at legitimately longer ranges, there's a massive difference.

I'm not sure how much recoil the MCX Spear has with the 277 Fury, given it's weight and suppressor, but if it mirrors typical modern .308's then inside of 300 yards I would still give the edge to 6.8 SPC due to lower recoil allowing for faster follow up shots. There is almost no discernable difference in recoil (very mild) between my 5.56 NATO upper and my 6.8 SPC upper, both running the same muzzle devices, barrel lengths and full powered ammunition on the same lower (as apples to apples as you can get).
 

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Unfortunately as normal politics got mixed in. Like following WW II and "cold war" ramp up U.S. wanted all NATO countries using same rifle and same cartridge. The FN FAL in 280 won the day then the U.S. said had to be 30 caliber and make similar energy to the 30-06. We settled on the 7.62×51 so FN reworked the FN FAL which won the day again.

Soon, there was a “Battle of the Bullets” that went as high as the White House and 10 Downing Street. Pres. Harry Truman and Prime Minister Winston Churchill even held a mini-summit, where rumor has it they struck a quid pro quo—the U.S. would adopt the FAL as its main battle rifle if Britain backed NATO adopting the 7.62 x 51-millimeter round. The M14 went on to become the shortest lived main fighting rifle in U.S. modern history.
Not being a U.S. rifle while the other 90ish other NATO allies began ordering personalized varients of the FAL we adopted the M14 and not not be only hold out offered to give Taiwan M14s if they would adopt it. Hard for a small country whose survival kind of depended on the U.S. not to take free rifles.

So the M14 only lasted seven years as the U.S. main fighting rifle before replaced by the AR 15/M16/M4. All while some countries are still fielding the FN FAL. What if the SIG Spear in 6.8×51 follows the M14 as a seven year or even less rifle we drop billions of dollars into before discover it's just too much rifle or with use proves to have issues like the M14 did plus being unusable in full auto fire for most 11 Bravos?

In five years long before the Spears filter through all the services we could see something like the HK416 design in 6.8 spc II in full testing. I sometimes wonder if General "Mad Dog" Maddis (great supporter of the M4 in 6.8) had not got tangled up in politics if our armorer's were pulling in M4's to inspect the lowers as swapped on "improved" uppers in 6.8 spc II? Fix the weak gas tubes, swap from Carpenter 158 to a more durable steel for bolt, improved cam pin and called it done.

Pull in the millions of M14s from warehouses and service, rebarrel in 6.5 Creedmoor where they have 40% greater chance of making accurate hits out to 1,000 yards than 7.62×51, 12 pounds of free recoil compared to 27 pounds in 7.62. The SIG Fury/6.8×51 makes 18-22 pounds of free recoil according to preliminary reports making it almost double the recoil of a M14 in 6.5 Creedmoor. Was somebody smoking weed with Bill Clinton? In full auto that's going to rock a 140 to 180 pound infantryman in F.A. fire.

Make the M14 40% more accurate, longer range and less than half the recoil rhen basically every problem with the M14 goes away making it good for another twenty years on the modern field of combat. New uppers for existing M4s, just barrels for M14s and the Fury has no real advantage except for Tier 1 teams to use for specific missions.

An infantry squad with two SPR/SDMs carrying M14s, SAW gunners running 6.5 or 6.8 based on theater and expected range of engagements then the bulk of infantry with 6.8 M4s would probably be more effective, handle current needs on the cheap while the "right" replacement has another decade or so of development. Uncle Sugar jumped on the Spear too quickly not thinking extending life of existing weapons with small upgrades in better cartridges till we actually developed a quantum leap in main battle rifle technology. While a nice rifle the M5 is not a quantum leap and is by no means cost friendly.
 
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An older brother was special forces in Nam, he hates AR15s still to this day has never owned one. Funny thing is he only used(carried) one over there for a week and not active. He hates them because they were plastic and the M14 was manlier in 1968. What he did say was they broke a lot of bolts and 20 rounds doesn't last long full auto.
I've had several over the years including some very expensive custom built double lug versions. Personally I don't like the mag release and how long it takes to do a mag change, I also try to keep my rt hand on the grip and charge with my left. IF they would set it up like AR15 controls with a rail for optics on the receiver they could be an option.
 

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Unfortunately as normal politics got mixed in. Like following WW II and "cold war" ramp up U.S. wanted all NATO countries using same rifle and same cartridge. The FN FAL in 280 won the day then the U.S. said had to be 30 caliber and make similar energy to the 30-06. We settled on the 7.62×51 so FN reworked the FN FAL which won the day again.


Not being a U.S. rifle while the other 90ish other NATO allies began ordering personalized varients of the FAL we adopted the M14 and not not be only hold out offered to give Taiwan M14s if they would adopt it. Hard for a small country whose survival kind of depended on the U.S. not to take free rifles.

So the M14 only lasted seven years as the U.S. main fighting rifle before replaced by the AR 15/M16/M4. All while some countries are still fielding the FN FAL. What if the SIG Spear in 6.8×51 follows the M14 as a seven year or even less rifle we drop billions of dollars into before discover it's just too much rifle or with use proves to have issues like the M14 did plus being unusable in full auto fire for most 11 Bravos?

In five years long before the Spears filter through all the services we could see something like the HK416 design in 6.8 spc II in full testing. I sometimes wonder if General "Mad Dog" Maddis (great supporter of the M4 in 6.8) had not got tangled up in politics if our armorer's were pulling in M4's to inspect the lowers as swapped on "improved" uppers in 6.8 spc II? Fix the weak gas tubes, swap from Carpenter 158 to a more durable steel for bolt, improved cam pin and called it done.

Pull in the millions of M14s from warehouses and service, rebarrel in 6.5 Creedmoor where they have 40% greater chance of making accurate hits out to 1,000 yards than 7.62×51, 12 pounds of free recoil compared to 27 pounds in 7.62. The SIG Fury/6.8×51 makes 18-22 pounds of free recoil according to preliminary reports making it almost double the recoil of a M14 in 6.5 Creedmoor. Was somebody smoking weed with Bill Clinton? In full auto that's going to rock a 140 to 180 pound infantryman in F.A. fire.

Make the M14 40% more accurate, longer range and less than half the recoil rhen basically every problem with the M14 goes away making it good for another twenty years on the modern field of combat. New uppers for existing M4s, just barrels for M14s and the Fury has no real advantage except for Tier 1 teams to use for specific missions.

An infantry squad with two SPR/SDMs carrying M14s, SAW gunners running 6.5 or 6.8 based on theater and expected range of engagements then the bulk of infantry with 6.8 M4s would probably be more effective, handle current needs on the cheap while the "right" replacement has another decade or so of development. Uncle Sugar jumped on the Spear too quickly not thinking extending life of existing weapons with small upgrades in better cartridges till we actually developed a quantum leap in main battle rifle technology. While a nice rifle the M5 is not a quantum leap and is by no means cost friendly.
HK already made a 6.8 SPC 416 back during the trials. Take a look at Gary Roberts slides from 2008 that I and others have posted around the net. It's towards the end where Roberts lists the merits of his recommendations for the MURG implementation.

Keep 5.56 for training purposes and swap the uppers to run 6.8 SPC for use out in the field. If you want to cross train with drop and drift, 77gr Razor Core in 5.56 has nearly identical velocity and BC as 110gr OTM in 6.8 SPC for training out past 300 so you even have a good training proxy for midrange precision shooting. I get 2586 fps from 77gr razor Core in my 16" 1:7 5.56 NATO barrel from DD and 2600 fps flat from Hornady 110gr OTM in 6.8 SPC, 16" 1:11 SPC II barrel also from DD.
 

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Btw I literally implemented that very recommendation myself due to 6.8 ammo costs. The two uppers are clones aside from the 5.56 wearing the lower cost Viper PST Gen II while the 6.8 uses a Razor HD Gen II-E.
 

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At 25:30 the 6.8SPC is suggested using a higher operational pressure along with a better bullet.
I think its important to understand the revolving door nature of the military industrial complex. Some General or Generals internally promoted this for their own benefit. They were probably on the source selection board too. Then after award, they retire and take a seriously high paid job with SIG. This happens in every channel of the military with every new acquisition. And as a result the American tax payer gets stuck with some ridiculous costs at a dubious increase in value to anyone including and especially soldiers.

So they can come up with all of the fancy language and "peer" matching they want to. The simple fact is that we will always see increasingly complex and sophisticated implementations in every new weapon created.

This platform will not be the next AR. It will always be extremely expensive and the ammo will be scarce to non existent for us civilians.

The Army teams that load up AR ammo make it so hot that after one firing the primer pockets are expanded and the brass is useless.

At 80K psi I cannot imagine that brass being anything but useless after one firing. And having seen the diagram of the case it does not seem likely that it could be full length formed either, steel is not malleable like brass. I would guess you could neck down a 308 case and get very close to the 3K FPS of this new round. But that would not have landed Mr General a cushy retirement job where he signs on with a million to multi million dollar bonus thank you very much.

So here is a platform that civilians will likely never see that uses ammo that civilians will likely never be able to either afford or obtain. And with Biden recently moving to prevent Lake City from selling AR ammo to civilians I think this is just a fore runner to cutting civilians out of access to military grade weapons. Everything has a first step.
 

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Although not applicable for the 6.8x51 yet, according to this article, the Army has decided to purchase polymer-cased ammo for existing 7.62x51 weapons. The contract is with PCP Tactical who has been working with the Army for a number of years. From what I understand, a reduced-range version of the new 6.8x51 is being designed, but I have yet to see the full specs. There has been speculation that the reduced-range ammo would be used not only in training but also in CQB and other situations where the full powered cartridge is not needed. It will be interesting to see if the reduced-range ammo will be loaded into polymer cases as well.

edited to add: According to its website, PCP currently manufactures 6.8 SPC polymer-cased ammo. It is the first I have heard of it.
 

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The Army is currently fielding M110A1 which is a HK417 that is modified to US Army spec. for DMR role. They claim its an interim solution until the NGSW project was completed and the results of that start to trickle down to troops in 2024 (from the articles I read).

The M110A1 is basically a 16" barreled HK417 ( 7.62x51mm) intended as primarily a DMR rifle optimized for engagements between 300-600 yards. For that role, I think 7.62x51 from a 16" barrel with modern NATO spec loads is indeed a great solution. 277 Fury would serve that role even better as it has a flatter trajectory and delivers more energy, it's a rifle man's rifle.

I think we can all agree that 277 Sig Fury and MCX Spear is a very high performance cartridge / platform that delivers some serious real world performance BUT, and it's a big but, it is NOT well suited to typical engagement distances of 0-300m with occasional use out to 500 aka the infantry 1/4 mile for a variety of reasons:

1. Recoil
2. Cuts ammo capacity down drastically compared to 5.56 or even 6.8 SPC
3. System is much heavier and somewhat bulkier than a small frame AR-15, so it's going to be slower to transition between targets, more difficult to shoot and maneuver and fatigue will set in much sooner, especially when you load it up with a nearly 1.75 lb 1-8x LVPO optics package, light (6-9oz) and IR package (8-10oz) and possibly a Bipod (13oz to 1lb) on top of it all plus a 20rd mag that weighs 1.5lbs loaded. And this is still brass / steel cased ammo, so it's not ultra lightweight polymer ammo.

I don't think the 80k psi allows for polymer cased ammunition to be used, but you could make 6.8 SPC in poly cased so it's as light as 5.56 brass cased. I still contend that the ideal solution would have been 6.8 SPC to replace 5.56 (Roberts MURG concept) and 277 Fury to eventually replace 7.62x51mm for DMR and Machine Gun roles.

The name of the game is suppress and maneuver, lets face it, bigger more powerful calibers suppress better than smaller, less powerful calibers. 6.8 SPC will suppress better than 5.56, but 7.62x51 or 6.8x51 will suppress better than 6.8 SPC and obviously the larger cartridges give you legitimate long range capability that 6.8 SPC does not.
 

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My understanding is that there will be several types of ammo used. There will be at least one reduced power load designed for CQB/Urban environments. Although the only polymer ammo that we know about is for 7.62x51, it is likely that the reduced power load for the 6.8x51 would be about the same pressure, so the potential to use polymer there also is good.
We don't know yet what the pressure limits of the polymer ammo is, but True Velocity has stated that they could make an 80,000psi case. If that is indeed correct, they need to demonstrate it. The bases of both True Velocity and PCP cases is steel already, as is the SIG Hybrid.
 

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One of the articles I had read a while back stated the reduced power load was intended for training to cut down on wear / cost and runs at 55k-60k psi like typical rifle ammunition.

The 80k psi loads are for duty use where the performance matters. The lower pressure training fmj is also full brass while the high pressure stuff uses the hybrid case obviously.
 

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As mentioned in my previous post the new M5 in 6.8×51 is going to have four times the recoil of an M4 in 5.56. Can feel your average 11 Bravo already practicing their flinch and riding the muzzle to the sky in select fire. Like others have mentioned I am training more with 5.56 than 6.8 because of 30% more powder being poured in each case. That said, 6.8 only adds 1.25 ft/lbs of recoil over 5.56.

Just received 16 pounds of H322 as realized only had 20 pounds left in locker. Scored an additional 15 pounds of Reloader 7, 8 pounds of H355 and have about 24 pounds of AA2200 in past two months. Realized have what seems like a metric ton of Vihtavouri powders from a local vendor that stocked heavy following Sandy Hook and had never done reloading supplies but had so many requests during that panic he decided to go in head first.

Soon as panic ended people went back to their regular vendors had used for years buying their preferred powders and Vihtavouri just is not that popular. He began marking it down till one day came in his shop and all Vihtavouri powders were marked down to $6 per pound and he had a huge supply of HP-38 which had never used at $10 per pound. Even worse for him he had three or four times what was on shelves in back room.

Bought entire inventory of Vihtavouri at $5 per pound, HP-38 at $8 per pound, put in one of my OSHA lockers keep odd powders not used much because it had room and forgot. Realized doing inventory while been stuck at home with broken foot past three weeks have over 20 pounds of Vihtavouri N120 which sits just one slot below H322 with AA2200 being a bit farther down. Going to have to work up a load for all that 120 and think the N130 and N133 will work in 6.8 especially for heavier bullets. Been putting together some ladders with each while on injured reserve to test when back able to walk.

Doing the same loading tests in pistol ammo with all the HP-38. Bought another 5,000 CCI #41s and several jugs of powder from newish vendor of late and rep asked if actually burned as much powder was buying. Said yes and have dealer pricing with two vendors but they have been out of stock on what need. Sent me a dealer app, filled out with companies Federal I.D. number, Sales & Use tax number and was just approved as dealer. Have another 24 pounds of H322 and 10,000 more CCI #34s on top of current heavy inventory of both #41s and #34s. Looks like time to switch back to lobbing 6.8s. Just added another 6.8 Mini and about finished with two more 6.8 ARs so when foot heals going to bust some steel.

About to build a pair of AR 10/SR-25s in 2-Fity Hillbilly which won't be able to get military projectiles but bet it runs close to the 6.8×51 in range. Scored a huge buy in steel core 7mm projectiles so cheap was silly so will basically be loading an upsized version of M855 in 7mm-08 to feed AR 10s. Too many good options out there doubt I will chase a 277 Fury unless SIG wants to mail me one...
 

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Agreed there are other very good options other than 277 Fury for AR-10 / MCX Spear sized battle rifles. Even the venerable 7.62x51 / .308 is still a very capable cartridge. Or there is 300 Win mag which is a brute. Not sure if anyone makes an AR-10 in 7mm magnum.

But yah, I have transitioned to shooting my 5.56 upper more than my 6.8 SPC upper which was the original recommendation of Gary Roberts in the 2008 NDIA presentation. Train with 5.56, fight with 6.8 SPC. Identical configurations, even running on the same lower with very similar recoil. While distinguishable, it's not significant like the jump from 5.56 to 7.62x51mm.

According to the DoD testing I have, the jump to mid-powered full caliber cartridges like 7.62x39mm, 6.8 SPC, 6.5 Grendel is around 40% increase. The jump to 7.62x51 is 140% and we all know your average shooter (including in the military) is not going to handle that very effectively. While the best shooters will utilize it efficiently, the average guy or gal is going to be employing mostly anti-aircraft fire if you get my drift.

Although I do still consider my 5.56 upper to be a "backup" and not just a trainer due to the fact that ammo is vastly more accessible should 6.8 SPC ever go completely out of production / availability disappears and my reserve of 6.8 ammunition were to be become depleted (foreign invasion, SHTF repeatedly and on a daily basis) or compromised (such as house fire etc.). While 5.56 is not optimal, it is still lethal, it just has more limitations than 6.8 SPC, but there are work arounds for some of them. You fight with what you have or can get, not with what you wish you had or want to get.
 

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Thinking on US military cartridges has changed since the 2000-2010 time frame when the 6.8 SPC was developed. Within a few years, our enemies had changed tactics and begun launching a significant percentage of attacks from beyond 550 meters, beyond the effective range of 5.56x45 platforms (over 25%, according to Jim Schatz's 2016 NDIA presentation) . Even Jim Schatz, an early proponent of the 6.8 SPC had changed his mind and had begun to argue for each infantryman to wield a weapon with an effective range of 800m. He argued for 1200m for the squad automatic weapon. It appears that the NGSW program was based around similar numbers.

It is clear that the Army sincerely hoped for a significant weight reduction of the NGSW cartridge. The hope was clearly something much closer in weight to 5.56x45 than 7.62x51. They did not get it. This has thrown a monkey wrench into plans. In the meantime, there had been steady improvement with polymer-cased 5.56x45 and 7.62x51 ammo, so by the time the 6.8x51 was introduced, a polymer-cased version of the 7.62x51 was available that was lighter than the new cartridge. Goodness knows how this will affect future plans. It looks like the best things that the NGSW program produced are the optic and a lighter SAW, the M250.

I think that SOCOM is still looking at 6.5 Creedmoor. At this point in time, a polymer-cased 6.5 Creedmoor may be considered close enough to the 800m/1200m goal.
 

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But, I still contend that body armor is a mixed bag even with all of the modern technology. I know, I have a pair of Hesco U210 plates, $700 each. 3.9 lbs per plate, less than 1/2 in thick, multi-curve, shooters cut. Maximizes mobility, minimizes weight and bulk while offering protection against special threats like the newish M855A1.

BUT, in training, I don't feel like I'm bullet proof. Some guy on full auto could just pepper me and get hits in my shoulders, neck, face, head, thies, abdomen or pelvic region and I'm DONE. Or any lateral (side) shot, because I only run soft armor on the sides and the hard armor side plates offer VERY LITTLE coverage and inhibit mobility.

Regardless of how good the armor is at stopping bullets, it doesn't cover enough of the body to make you a walking tank, not even close and any skilled shooter can adapt to using a modified doctrine of 1 or 2 in the chest to disorient, 3 to kill / disable by a hit to an unprotected area. With low recoil cartridge's at CQB distances it's perfectly workable. And at extended ranges, precision shots can just circumvent protected areas all together (aka taking a precision shot on a target's unprotected area who isn't aware your there in an ambush).

The other issue with going through armor is that ANY AP load that penetrates the armor is going to Ice Pick, your not getting an expanding projectile through the armor that creates wounds 5x the size of the projectile. And the penetrator core is smaller than the bullet diameter which reduces it's effects further. So an AP round in 277 Fury, .308 or any other full caliber is still half the diameter of 9mm ball ammunition. It's like shooting someone not wearing armor at close range with handgun ball loads....lethal if in the right spot (aka shot placement, penetration depth), but far from ideal with non-vital hits.

That should tell you how ineffective 5.56 AP is, 5.56 is already a small diameter bullet and the AP penetrator is even smaller. With larger calibers, at least the AP core may be as big as the 5.56 bullet and act like an ice picking M855. That's when volume of fire or shot placement become critical.

Either you hit the CNS/Heart/Liver with non-expanding penetrators to take down the target or you kill them with volume of fire (many small holes equal one big one). My argument has been that enemy combatants may be just as effective to place one shot in the chest to the armor to disorient and damage the target (broken ribs, wind knocked out of them), then place another shot or several shots on unprotected areas to disable / kill.

Think about VMax hitting an enemy soldier in the throat, neck, T-box, shoulder, femoral artery, pevlic region....they aren't getting back up. You will literall blow fist sized holes in arteries and limbs or the gut (extraordinarily painful). That's no different than 5.56 doctrine now of two in the chest, one in the head for a failure to stop due to the failures of M855.

So I see 6.8 SPC as low enough recoil you can still shoot fast, bring more energy to an armor plate center mass hit to disorient then finish off with hits on unprotected areas at CQB distances. That's kind of what US soldiers adapted to in order to compensate for M855's failures, it may be re-adopted to defeat armored threats without AP ammunition which has very marginal terminal performance after penetrating the armor in any caliber, but especially in 5.56.

I really don't think 277 Fury is going to produce significantly better terminal performance after penetrating armor, so it's likely multiple center mass hits would be needed or a single center mass hits with follow ups to unprotected areas. I predict the wide spread use of armor is going to necessitate a return to marksmanship and tactics even with technology.

There's no perfect armor just like there's no perfect bullet.
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I don't argue with the 6.5 guys, just wait for their bolt to break and keep making hits with my 6.8 they were missing with their 6.5 and whey they got frustrated slinging rounds till they break their gun. Most things being equal a 6.8 bolt will outlast two or three 6.5 bolts. Dope it right or not doesn't matter the cartridge. I have a few more inches drop at range, big deal, the shots still hook up.
I think that was the general conclusion of the AMU when they tested y.y x 43mm. They literally tested 6mm, 6.5mm, 6.8mm, 7mm and some 7.62mm in a trimmed down 43mm case based on the parent case from Remington. The drop and drift between 6.5 and 6.8 was not significant for maximum engagement distances out to 500 yards, past those distances the more ideal Exterior Ballistics of 6.5mm projectiles starts to pay off.

The problem is, those distances aren't the norm, they aren't really the intent or scope of the Assault Rifle's use cases either. They are a rather rare set of circumstances that can become common in certain environments that small units operate in, such as the mountains of Kandahar, such situations make far more sense to utilizing full powered cartridges like 7.62, 6.5 Creedmoor or 6.8 x 51mm Fury. All three of those will out perform 6.5 Grendel in terms of on target damage. The 6.5 Grendel is a mid-powered cartridge attempting to be a full powered one and it just makes too many compromises at closer ranges, through barriers and reliability to justify the small gains past 500 for some very rare circumstances. Most assault rifles are not even equipped with optics suited for those ranges. It's an example of a "paper tiger" cartridge looking to solve an unrealistic problem.

I've seen several articles suggesting most SF only see the need an optimal system for 0-400y, but 0-500y gets them to the "infantry 1/4 mile" as they had hoped for wider spread adoption over 5.56. In some ways, 6.8 SPC is like a beefed up 5.56, it uses a somewhat intermediate length bullet profile, with a medium sized case. Almost like a 5.56 "Heavy".

I shoot 77gr Razor Core from IMI in my 5.56 upper. I get 2585 FPS for the 1:7" NATO spec barrel (Daniels Defense), a little slower than the slightly hotter Black Hills 77gr that typically nets around 2650~2670 FPS from that same barrel length. But I get 2600 FPS flat from factory loaded 110gr Hornady and 110gr S&B FMJ. The 110gr Hornady OTM has a bc of 0.360, both 77gr's, weather Black Hills or IMI's, both are about .362 BC G1. What's the difference in drop / drift between 77gr and 110gr...? ZERO. You could literally use a BDC calibrated scope for 77gr 5.56 with 110gr 6.8 SPC.

The difference is that 77gr OTM in 5.56 has horrible barrier blind performance, especially against auto glass, somewhat inconsistent yaw at closer ranges (not as bad as M855 or XM193, but still not as consistent at 110gr 6.8 SPC). 77gr also destabilizes too fast through glass and doesn't penetrate adequately. 110gr OTM in 6.8 SPC is much more stable and punches through, basically doubling the performance of the venerably 62gr ATK bonded SP load in 5.56. But the ATK bonded SP loaded by Federal has a garbage BC of .224...it's a CQB load only and the wounding of that load is not as good as 77gr OTM's on direct hits.

For 5.56, your always compromising considerably in one area or another. There is NO load in 5.56 that provides good glass performance, good medium range performance and good close range performance where damage needs to be maximal. M855A1, the "newish" replacement for M855 still does not perform well against auto glass and the wounding profile is less than 110gr 6.8 OTM's or other 6.8 loads. You can't even buy M855A1 in 5.56 as a civilian in any quantity, certainly not consistently. MK318 was probably the best general purpose 5.56 load worked quite well over a variety of conditions, it was like a lesser version 110gr OTM. It is now defunct, out of production all together because they forced a standardization on M855A1. So what's left for 5.56 as a general purpose combat load? Nothing. Everything is a significant compromise in one area or another.

There are several 6.8 SPC loads that good all around performance such as 110gr OTM, 110gr PTS, 110gr Nossler etc., not to mention more exotic bullet designs that perform even better in specific situations like 120gr SST, 120gr MKZ, 95gr TTSX. It's just a very consistent performer relative to 5.56 with similar bullet designs. Now 5.56 can work quite well with the right load in the right context, but it's a marginal cartridge, meaning in order to get desirable performance, the conditions and load choice need to be "ideal" vs. the much more real world conditions of "less than ideal" or "downright sucky". We don't want to plan for "ideal", we need something that still performs reasonably well in "less than ideal" and "downright sucky".
 

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Again it all depends on the application. If your up in the mountains looking from mountain side to mountain side, large rolling plains of the mid-west, or even the foothills of PA, 6.8x51mm makes a lot of sense with a 1-8x or 1-10x. If your in woodlands, urban, home defense or typical infantry applications (vehicle mounted), 6.8 SPC makes more sense and we KNOW for a fact that 6.8 SPC AP can defeat IV out to at least 100 yards. There are other AP designs that were tested than the one below, the 2008 Roberts NDIA shows a 6.8 Tungsten load modeled more after 5.56 M993, no idea what the capabilities of it were, but I'd imagine it's at least as good if not better than the SLAP round below.

Better AP ammunition might improve that further, but these were brass bodied tungsten core bullets that provided about 20 yards more AP range than 5.56 (the 5.56 version was rated to 80 yards). 100 yards for IV isn't bad given that 6.8 SPC endows very similar capacity, recoil and platform characteristics as 5.56. At much longer ranges you have more time to place precision shots and shoot around the armor...its at close range where you just need to get hits on the target as fast as you can. With LVPO's and the accuracy of 6.8 loads it's not too difficult to group 6-8 inches at 300 yards...that's head shot territory, I'm talking about field conditions with imperfect holds under time, stress etc.

There are NO LEVEL IV helmets or face shields (T-box). So my point is, the AP capability is there for CQB, for anything with range...how much does that matter? At 300 yards your a lot more likely to engage prone or static targets trying to take precision shots back at you, that's where precision shots start to matter. I may be wrong, but I think there are a lot of practical areas to place hits on target that will disable or kill that are NOT protected by hard plates in the real world, assuming they are even wearing hard plates. US Soldiers loose their lives despite wearing hard plates, soft under armor vests, nut plates, ballistic collars etc. And what they found is that makes them too slow to be combat effective anyway, so many SF units pared all that down to just a pair of hard plates and soft side plates for the best balance of mobility.

Too many guys were still taking hits to limbs or other areas that led to fatalities and they were having difficulty engaging the targets at speed who were not wearing armor at all. Plates won't stop a FMJ to the thy, pelvic region, shoulder, neck, head, face or side shots. Armor works, but it has limitations regardless of it's threat ratings due to limitations in coverage, weight and maneuverability.

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