We've Missed the Boat By Not Making 6x45 The Primary AR15 Cartridge

[[email protected]]

6x45 in a factory short action bolt gun is what I like to see. I have been trying to buy the 6x45 barrel from midway usa for a few years. It's always been I have the cash and they don't have the barrel or they have the barrel and I already spend the play funds.

 

[barnbwt]

Which has been an abject failure in and of itself. In the current wars we're shooting about 250,000 rounds for every kill (up from about 100,000/kill in Vietnam). In other words, the entire ammo loadout of an infantry COMPANY isn't close to enough to get even one expected kill. Put another way, our rifleman are noisemakers, not enemy killers.

Scenario:
Patrol comes under fire. It is my understanding (not military here) that the procedure is to seek cover and/or concealment on the way to cover while returning fire in the direction of the enemy if its location can be determined. This is the 'ambush's scenario the M16 was originally designed to be controllable on automatic for, though the modern tactic is rapid semi-auto fire to better conserve ammuntion & keep the 'cone of fire' in a smaller though still indeterminate area until the enemy can be positively located, then fixed & maneuvered upon 'till death.

At no point of that cycle is any particular enemy soldier being shot AT, just his proximity. From what I understand, head and COM shots have become far more common in the last war cycle since electronic and magnified optics have supplanted irons. This would indicate that the "aimed fire" portion of combat where one group advances on a known target by flanking while a second distracts or fixes them in place with suppressing fire, has gotten considerably more effective and accurate (heck, the 'us' vs. 'them' infantry casualty due to small arms figures should be enough to prove that), despite no significant change in ammunition. I would focus on that portion of combat to tout the benefits of a new cartridge, though I suspect its range is almost always well within the effective reach of 5.56.

Neither suppressing fire nor reactionary fire while breaking contact require notable accuracy, and have already been made far more efficient by enforcing semi-auto rapid fire discipline in lieu of automatic bursts. Further enhancement of accuracy beyond 5.56 is unlikely to change anything. Similarly, these actions typically do not focus on specific targets by my understanding & are not fired with the expectation of scoring a hit on an aimed opponent (outside of targets of opportunity) so ballistic performance on a target behind cover is unlikely to be a factor (unless stepping up considerably to a much more powerful battle rifle cartridge capable of defeating some light cover, with all its disadvantages). Incidentally, besides training & good old waste, these two areas of combat are where the vast majority of ammunition expenditure necessarily occurs (because it simply doesn't take very long to wipe out an enemy patrol once all five idiots are exposed to the flanking team's fire, compared to distracting them long enough for that team to move into position)

So focusing on the bullets/kill number is completely missing the mark. An awful lot of engagements consist of a single guy dumping a mag into a far-off patrol then immediately running away & hiding before our guys can even get a return salvo sent his general direction; no 'magic bullet' will convince him to stick around long enough to get his head shot off. I'd say hits/kill or wounded/kill ratios would be far more useful in determining how effective our bullets are at doing what bullets are meant to do, though I honestly don't know if it is practical/possible to track those. Without changing anything but iron sights, we're consistently scoring better hits on targets, and leaving fewer enemies to ride home on gurneys than ever (granted, the latter somewhat due to our present cowardly opponents' neglect for their own wounded comrades)

TCB

 

[barnbwt]

In some states .22 was determined inadequate for deer long before the 5.56 came on the scene.

In some states, you're only allowed to shoot straight-wall cartridges under a certain overall length --I wouldn't rely on the wisdom of laws, here (or ever )

Just a guess, but perhaps that's because of a quirky pressure curve, which wouldn't help a gas gun.

Is that a real issue with 6x45? Genuine question. I thought it ran alright in ARs.

6x45 in a factory short action bolt gun is what I like to see.

Howa just came out with their super short action, I know it's offered in Grendel, so I assume 6.45 is doable. One of the Ruger bolt guns should be viable as well, for an easy conversion.

TCB

 

[mshootnit]

The late Greg Rodriguez examined this issue in Shooting Times: http://www.shootingtimes.com/ammo/ammunition_st_proposal_200808/

 

[CoalTrain49]

In some states, you're only allowed to shoot straight-wall cartridges under a certain overall length --I wouldn't rely on the wisdom of laws, here (or ever )

I don't think a straight walled cartridge can be defined as a modern rifle cartridge. So the states that you refer to have made all modern rifle cartridges illegal for deer because of a high density population. The state that I live in has a modern rifle season but .223 and all 22 cal. rifles are illegal.

I know a lot of people shoot deer with their AR's and that's fine with me, I honestly don't care. You can hit them with your car if you want. Bullet tech has made .223 suitable for deer but you can't use a Barnes TXS in combat.

I have a 357 bolt gun. Much better 100 yd deer rifle than any .223 on the planet. Things fall down when you hit them. No BS.

 

[barnbwt]

So your point is we should replace our M4's with 357mag AR conversions or 300 blackout? How's the 357 out to 300 yards?

 

[Phaedrus/69]

There would be some advantages to necking up to 6mm, 6.5mm or even 7mm. But if we keep the same case and require it to fit in the same rifle with just a barrel swap then you will get minimal improvements.

I'm not sure about the cost/benefits ratio of starting over with a clean sheet of paper to design a new rifle at a point in history where small arms have reached their nadir in the overall importance in warfare.

 

[MachIVshooter]

Face it, the AR15 is simply chambered in the wrong round.

 

[roscoe]

Our rifle tactics suck just as badly as our rifles - actually arguably far worse - but that's a different topic.

I am kind of curious as to the errors of small-arms tactics in the current military. What exactly should they be doing differently? And would it have made a difference in any conflict since the Civil War?

 

[Phaedrus/69]

I kind of doubt a 6mm bullet would have a lot better terminal performance given the requirement to use FMJ. For civvies I personally think the 5.56 is a pretty good round. With modern projectiles that aren't FMJ it's extremely lethal yet easy to shoot well. Hard to imagine a human not being stopped in his tracks by a couple of 55gr GMX bullets at 3,000 fps! I think actual experience has borne this out.

 

[Coal Dragger]

Meh, my experiences in Iraq as a USMC infantryman in 2004 with an M16A4 (20" bbl) were pretty positive at least in the terminal ballistics area. Not many others I know who were in the USMC had a lot of negative things to say about cartridge performance at least with 20" bbl rifles that get the most out of M855.

Friends of mine who stayed in and deployed multiple times after the switch over the M4 with the 14.5" bbl didn't voice a lot of complaints with the cartridge either.

The biggest complaint I heard or had was that at extended ranges beyond about 300-400M the M855 round just doesn't have a lot of energy left. MK262 77gr 5.56mm NATO helps quite a bit here, as does the issue of 7.62mm NATO chambered rifles like the SCAR H at the squad level in some units. In Iraq this was not an issue anyway, Afghanistan I understand was different but I have no experience there since I didn't deploy there.

 

[kBob]

Um,


AR15 in 6X45 was the first AR non .223 offering back in the 1970's.

It was pushed by an out fit called "Old Sarge" that was a regular advertiser in the Shotgun News.

They also sold parts and build kits.

I note they don't seem to be around anymore, at least by that name.

-kBob

 

[grampajack]

I don't think there's anything to be gained by increasing the diameter of the bullet. The only real problem with .223 is that it traditionally has had a low BC. Had it been designed from the ground up for 80 gr. (ish) bullets, it would be just about perfect. Just a slightly longer receiver and magazine, not enough to even really notice. My dream AR would do an 80 gr. .223 bullet at around 3,000 fps from a 16'' barrel. Slightly longer receiver, and just a little more kick, but good returns in range and accuracy potential.

I would even be in favor of reducing the caliber to .20, in whatever length gets you the best BC. Then design a case around it that would get you 3,000 fps or so from a 16'' barrel. I think you'd be looking at similar terminal performance as M193, but it would cut the wind better.

The way I see it, the concept of an intermediate cartridge is good for creating traumatic wounds at close range, sort of as a replacement for SMGs. That way you get a small, lightweight package with low recoil that can wound better than pistol cartridges, plus extend their range from 50 to about 200 meters. That, in my mind, is the epitome of the assault rifle concept. If you try to make it bigger and better, you just end up with a jack of all trades, and master of none.

 

[barnbwt]

I am kind of curious as to the errors of small-arms tactics in the current military. What exactly should they be doing differently? And would it have made a difference in any conflict since the Civil War?

I believe the claim is that every shot should be aimed, because suppressing fire is wasteful, and that 6x45 is more amenable to that goal. Yup, the same argument used against repeating bolt rifles from waaayyyy back in the day.

 

[Tirod]

I note only two posts bring up the difference in barrel length from M16 to M4. That's a 5.5" difference and velocity is the main parameter in 5.56 ballistics. That downturn drove two programs to address the lesser amount of power delivered downrange, 6.8SPC and .458 SOCOM. And both concepts were based on having more power to knock down an enemy soldier.

That concept - to make them Dead Right There - has a lot of subscribers, but it does not have a good track record in combat, and further, has been something we worked to get away from over the last 200 years. Ignoring the history of why we have been reducing the size of bullets and the comparable amount of power they carry means not understanding the basic principles of what really happens in combat. It's as if the soldier is the only armed aggressor on the battlefield and his rifle the only tool available.

Far from it.

It also goes to thinking that we can train and maintain Expert class shooters across the board. If your MOS isn't pulling a trigger - it's not going to happen. Even then there are other items to maintain skills in. I don't see any advantage in keeping a surgeon's assistant out on the range every week to maintain Expert when their primary skill is helping to sew up my broken body damaged by mortar or IED's.

We can't afford to keep the DOD shooting to Expert levels. No country can. The days of having a force which is proficient with their main battle weapons never existed. Even Rome couldn't afford it. Somebody has to cook the meals and water the horses - swinging a blade around in melee rehearsal - even wooden swords - means not getting their primary job done.

Changing the length of the sword and making it two inches longer isn't going to do much, either.

Don't get focused on narrow concepts and ballistic minutiae. The AR does fine - even if we did cut nearly 6" off the barrel. Most aimed shooting engagements take place under 125m anyway - until then there simply isn't enough window of opportunity to see the enemy much less take a shot at them. They tend to hide behind things that stop bullets or maneuver out of sight as much as possible, all while their team mates are shooting at YOU and forcing you to keep your head and eyes off the target. Usually with full auto crew served weapons.

In the meantime you would be calling up indirect fire to suppress them.

It's not about one soldier with one rifle. It's about orchestrating the chorus of war. One small incremental change in caliber won't be a game changer and thinking that way isn't taking the big picture in.

 

[Llama Bob]

I've never heard of a 6mm anything being considered to replace the 5.56 NATO cartridge.

I thought all of the latest research pointed to the 6.8x43 and the 6.5x38 as the optimal cartridge.

6x45 easily outperforms both when constrained by the maximum bolt thrust of the AR15 platform. 6.5 Grendel is a non-starter because it feeds poorly and has an overly large case head that causes bolt and/or extractor failures. Worse, to match 6x45 or even .223 long range performance in 6.5 Grendel you have to push the both thrust up well above M855, which already is on the edge of breaking bolts. It is perhaps the worst modern cartridge design we've got.

6.8 SPC has some minor potential, but only for short range because those .277 diameter bullets have bad BCs at the weights you'd want to use.

6x45 gives you enhanced terminal performance while at the same time having long range capabilities on par with classic match .308 and posing zero risk to the AR15 platform since pressure and bolt thrust are unchanged from M855.

 

[lysanderxiii]

Yes, although not due to lack of external or terminal performance. The .7.62 accuracy load (designated M118/M118SB/M118LR/M316Mod0 and a few less formal things) has been pretty much the same since the 60s. There's just been some turnover in bullet and powder suppliers and some modest increases in BC as we learned how to make better match bullets.

M80A1

Improve terminal performance, perhaps?

Beside, there was no requirement, or lack of desired performance that drove moving away from M193 to M855. What happened was NATO was looking to standardized a second caliber, and they were going to choose the best cartridge available, from M193, and improved version of M193, SS109 and a British 4.85mm cartridge.

If you are getting something new, why not get something better?

 

[lysanderxiii]

Your point being what? You can get the same flat trajectory in 6x45 if you want to similarly decrease the BC.

.223 has literally no advantages. It's the mistake that won't go away

When you go to the heavy bullet you suggest, the trajectory is more like the M118 or M80. To get the flat trajectory, you find you are shooting the same weight bullets as the 5.56mm. Which don't have the down range performance of 5.56mm due to the lower BC....

 

[Llama Bob]

When you go to the heavy bullet you suggest, the trajectory is more like the M118 or M80. To get the flat trajectory, you find you are shooting the same weight bullets as the 5.56mm. Which don't have the down range performance of 5.56mm due to the lower BC....

If you want down range performance, both .223 and 6x45 have to go to the heavy bullets but there's substantial limits with .223. For example, the.223 77gr SMK has a G1 BC of .362 in the middle velocities, whereas the 95gr .243 is .460.

 

[CoalTrain49]

So your point is we should replace our M4's with 357mag AR conversions or 300 blackout? How's the 357 out to 300 yards?

Don't know. I guess it would be like using a mortar.

Where rifles are illegal for deer a PCC is a viable option to a shotgun. That was my point. Penetration is pretty good with 158's at 100 yds. I would venture a guess that most deer in the US are shot within 100 yds. I used to hunt with a rifle in the west and most of the deer I took were less than 100 yds. Out here archery and muzzle loaders have become more popular than rifles, which are legal.

I'm not making a case for using bows, muzzle loaders or a 357 in combat. Deer don't shoot back.

The original design for the M-16/5.56 NATO was a weapon using a 20" barrel. When the military adopted the M4 carbine things went downhill and they've been patching it up ever since.

But I think you know that

Barrel length SS109/M855 V4 bullet velocity V4 velocity loss
210 mm (8.3 in) 723 m/s (2,372 ft/s) 41 m/s (135 ft/s)
240 mm (9.4 in) 764 m/s (2,507 ft/s) 32 m/s (105 ft/s)
270 mm (10.6 in)796 m/s (2,612 ft/s) 29 m/s (95 ft/s)
300 mm (11.8 in)825 m/s (2,707 ft/s) 18 m/s (59 ft/s)
330 mm (13.0 in)843 m/s (2,766 ft/s) 23 m/s (75 ft/s)
360 mm (14.2 in)866 m/s (2,841 ft/s) 12 m/s (39 ft/s)
390 mm (15.4 in)878 m/s (2,881 ft/s) 14 m/s (46 ft/s)
420 mm (16.5 in)892 m/s (2,927 ft/s) 14 m/s (46 ft/s)
450 mm (17.7 in)906 m/s (2,972 ft/s) 9 m/s (30 ft/s)
480 mm (18.9 in)915 m/s (3,002 ft/s) 7 m/s (23 ft/s)
508 mm (20.0 in)922 m/s (3,025 ft/s) -

 

[VoodooMountain]

If you want down range performance, both .223 and 6x45 have to go to the heavy bullets but there's substantial limits with .223. For example, the.223 77gr SMK has a G1 BC of .362 in the middle velocities, whereas the 95gr .243 is .460.

Running those numbers through hornady's ballistic calculator shows the 556 retains more velocity and has about the same energy at 400 yards which is outside of the realistic range for good terminal performance for either round.

The 6mm offering just doesn't offer much of anything over the 223. It throws the same weight bullet (55) at about the same velocity while it also has the options of bullets up to 100 grains but they are moving at 7.62x39 or 300 Bo velocities but with a much smaller bullet. You gain about nothing if you use the same case for both rounds.

As far as me taking up my disbelief of a 100 grain bullet with a mv of 2400 fps being a good or even adequate medium game option out to 350 yards with nosler, you must also remember nosler makes a 60 gr partition for the 223.

According to your logic of keeping the impact velocity at 1800+ fps to initiate expansion to make a good clean kill, this 223 bullet would be good for cxp2 game out to 300 yards with a mv of 2950. Nosler states this bullet is good for medium size game such as deer but not to 300 yards. You say the 223 bullet just isn't an effective killer so with whom do I take up my argument now?

To make a good clean and effective kill requires more than bullet expansion and sometimes, as with hard cast, no expansion is needed. There is much more going on in terminal ballistics than expansion of the projectile.

 

[Llama Bob]

Running those numbers through hornady's ballistic calculator...

What did you run? Higher BC loads retain energy better, not worse.

Also, the max engagement range for M262Mod1 is 800y, not 400y.

 

[Coop45]

Which has been an abject failure in and of itself. In the current wars we're shooting about 250,000 rounds for every kill (up from about 100,000/kill in Vietnam). In other words, the entire ammo loadout of an infantry COMPANY isn't close to enough to get even one expected kill. Put another way, our rifleman are noisemakers, not enemy killers.

Our rifle tactics suck just as badly as our rifles - actually arguably far worse - but that's a different topic.

A lot of NVA will disagree, but since we are redesigning stuff lets go back to the Vietnam era entrenching tool. One tool will kill a lot of enemy an only needs repainting occasionally.

100,00x1 must be the army ratio. Marines availed themselves to other means if necessary. Napalm, Bombs, Artillery come to mind, but the entrenching tool is cheaper. Speak up I have a hearing loss.

 

[VoodooMountain]

What did you run? Higher BC loads retain energy better, not worse.

Also, the max engagement range for M262Mod1 is 800y, not 400y.

It's the velocity that makes all the difference. Run the numbers yourself.

The max range of 800 meters is about the capability of the sights, not the round and especially not the shooter.

If you want to make the argument that the 556 is consistently effective out to that range then why change anything?

 

[Sistema1927]

Woulda, coulda, shoulda.

BTW, Vietnam "body counts" were notoriously over inflated. I wouldn't use them as "proof" that US military marksmanship or tactics have devolved.