Best Caliber for M16 for a Battle Rifle

[deltaenterprizes]

The M16 in 223/5.56 has been claimed to be not the best caliber for a battle rifle.
Of the latest chambering available now for the AR15/M16 platform what do you think would be the best choice for the military to adapt for a new battle rifle?

[TurnipEaterDown]

Seems like a loaded question (pun accepted if not intended...).

Suppose it depends on the role.
There have been several developments for dedicated roles.

Seems to me like an overall useful design alternative would be the 6.8 SPC, or a 6mm ARC or 6.5 Grendel, IF increased cartridge performance were an identified requirement.
Of course, these all grow loaded weight & Cost, and /or sacrifice capacity.

Myself, I do sort of wonder why a 25 was jumped over -- most likely it just has to do with a lack of existance of a suitable bullet design for the role.

[Larry Gibson]

M16....a "battle rifle"?

Since when?

[rockrat]

I would lean towards the 6x45 or the 25x45. Only a different barrel needed

[WRideout]

There are a lot of considerations that go into the selection of a military cartridge. Aside from bullet diameter and weight, there is a question of whether the same cartridge can be used in multiple different weapons; as seen with the 30-06 in WWII. Then there is the aspect of logistics. Can the cartridge be adequately produced and supplied when needed? Aside from the technical aspects there is that national pride thing. "Our" cartridge should be better than and different from everyone else. According to Hatcher's Notebook The 276 Peterson cartridge was nearly adopted as US standard, until the idea was vetoed due to large stocks of existing 30 caliber ammunition. Along that line, the M3 grease gun which was chambered in 45 ACP, had a conversion kit for 9mm Para which was used by everyone in the known world.

Even if it was not the original intent, the M16 seems purpose built for fighting in dense jungle or close quarters. In that regard, the 5.56 Nato is probably the best choice. In a different theater, a long range weapon with a heavier bullet might be the answer. The M14 is the obvious response to that.

Wayne

[gwpercle]

M16....a "battle rifle"?

Since when?

LIKE !

[36g]

I'd go for a .264 caliber rifle cartridge along the lines of a necked down .308 (6.5-.308) in something like an AR10 platform with a short recoil gas system, 18" barrel. No hyper pressure cartridge, just a standard rifle cartridge configuration. Should reach out and touch well with a good BC bullet.

[deltaenterprizes]

M16....a "battle rifle"?

Since when?

It is being used as such and has had many complaints about being ineffective.
The platform has worked but the ammunition has shown to be anemic, so the inquiry is what available cartridge would improve the effectiveness.

[Finster101]

If you want to stay in the AR-15 platform 6mm ARC using 103-107 grain bullets, has very good ballistics and better range than 5.56. It only requires different mags, bolt and barrel.

[P Flados]

As noted previously, the AR-15 / M-16 class of gun is not really what most would call a "battle rifle". However, lets assume you just asking about a compact rifle (smaller than an AR-10) but better for what I will call mixed use (more longer range shots).

Also lets assume we use the context of today's most notable shooting conflict. Someone wants to volunteer to fight Russians in Ukraine where the gun really matters (would get used a lot).

In a role involving almost exclusively close range (clearing trenches), the capacity advantage of 5.56 probably makes it worth keeping even if occasional longer range shots are less likely to be effective.

In a role that combines more frequent longer distances and a reduced worry about running out of ammo when face to face with the enemy, the 6.5 Grendel or something close to it will have much better terminal performance. However, moving to an AR-10 sized gun with 7.62 x 51 would probably be better given what I would expect for the ammo re-supply situation at or near the front.

I would go with one of the "improved" rounds in a M-16/AR-15 type gun for general use only in the case where a good percentage of the guns in my zone are all in this "new cartridge".

The above is all pretty obvious. Also pretty easy to figure out are the trade offs between the choices in 6, 6.5 and 6.8 mm diameter rounds (ammo supply considerations, effectiveness with and without body armor at given distances, allowed weight of ammo / number of rounds to be carried).

Regardless of any personal desire, logistics do matter a lot when it comes to cartridge choice in most military applications. The exceptions are usually things like a dedicated sniper role or a Special Forces "raid" type activity.

If the OP wants to propose a specific role or setting where a M-16 class gun in something other than 5.56 is used by general purpose troops, more detail would be needed to first deal with the logistics issues and then narrow down the selection of actual bullet diameter.

[Combat Diver]

5.56 is going to be around for a long time. We see how the larger 6.8x51 does once combat troops start getting them and ammo stocked. The 6.8 is only for combat arms. All others with still be using the M4 and lesser extent the M16. M855A1 has shown to be a better performer over M855 but I still like to carry Mk318 or Mk262 and did for years in Astan. If I need more penetration had a mag or two of M995 AP.

[atfsux]

Seems like a loaded question (pun accepted if not intended...).

Suppose it depends on the role.
There have been several developments for dedicated roles.

Seems to me like an overall useful design alternative would be the 6.8 SPC, or a 6mm ARC or 6.5 Grendel, IF increased cartridge performance were an identified requirement.
Of course, these all grow loaded weight & Cost, and /or sacrifice capacity.

Myself, I do sort of wonder why a 25 was jumped over -- most likely it just has to do with a lack of existance of a suitable bullet design for the role.

This indeed needs to be answered before picking the rifle caliber. Weapons are designed according to the doctrine of war the army acquiring them employs. For instance, the M16 and the 5.56 rounds were developed with the doctrine in mind of mounted and airborne troops being delivered close to or at the battlefield and therefor likely to engage the enemy at distances of under 300 meters. Body armor was not really a thing in 1957, so there was almost zero consideration of the power to perforate anything other than the enemy soldier.

But today, while the rifle is still not the primary weapon used to kill the enemy (that would be artillery), we have seen the rise of effective body armor making it much more likely to survive torso hits at distance from 5.56 and 5.45x39 weapons. There has also been an emphasis on use of smaller and more adaptable units, such as special forces, rather than full set battle types of organizations, such as divisions or battalions. In these smaller units, the firepower of the individual soldier matters more. Quality of fire, not quantity of fire, wins today's battles more readily.

So while the average soldier still needs a light ammo load so as to not fatigue him on the march (for which 5.56 or 5.45x39 makes sense), it would be ideal if his rifle was able to reach out as far and hit as hard as the previous .30 caliber weapons of a few decades ago. Thus, the newer class of "mid-caliber" cartridges developed in the last 20 years like the 6mmARC, 6.5Grendel, 6x47Lapua, 5.8x42 and similar actually have a lot to offer and be considered.

I personally think the 6mmARC, throwing a 100grn. OTM at about 2700fps out of an 18in. bbl. is probably the optimum available today. Yes, it will recoil more than a 5.56 or 5.45x39, but nothing like a .308 or even a 6.5Creedmore. Put a suppressor on that puppy, and I'll happily put up with the slight weight and recoil penalties.

[Texas by God]

Wasn’t the 6mm ARC called the 6mm Lee Navy the last time it was tried?
I vote for the 6.8 SPC.
Only because I have one and like it.


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[Winger Ed.]

The M16 in 223/5.56 has been claimed to be not the best caliber for a battle rifle.

That's a bit of an understatement.
Even with more modifications and changes than a small block Chevy V8,
the M16 reminds me of futility sort of like putting lipstick on a pig.

[Pipefitter]

450 Bushmaster, because shooting something twice is just silly..........

[405grain]

The military requirements for a cartridge change over time. In example; when it was being evaluated for use by the Army one of the requirements for the 30-06 was that it had to be able to kill a horse with one shot at 1000 yards. Today that sounds bizarre, but when it was being tested scouts were on horseback. A scout on foot would take three times longer to relay intelligence back to their command than a scout on a horse. Criteria like this don't matter in this modern age, but there is one thing that I feel would be important in selecting an all around battle cartridge. A human struck in the torso by any rifle cartridge is going to be in some dire distress. Almost any cartridge that will fit in the AR platform can ruin a guys day. But, IMHO, to be truly effective I think that you need a cartridge capable of cracking an engine block after the bullet has already passed through a tire. When I was in the Navy, a Marine Corp shooting instructors taught us that the best way to disable a truck or other light vehicle was to take a side shot and aim for the top of the front tire. (if possible, targets don't always cooperate) This way you would simultaneously give them a flat and crack the engine block. We were using M1A's, and a 7.62 NATO round could get the job done at ambush distances. If you want a "battle rifle" I think that it needs to have both anti-personnel and anti-vehicle capabilities. Just my 2 cents.

[country gent]

Upping bullet weight and performance puts us back where we were with the garand and M-14,The new troops cant handle the recoil or added weight of the load out of ammo.

[Finster101]

6mm ARC is not significantly different in recoil, very little in weight and probably 18 in the same size mag that is currently 20.

[DDriller]

6.8 SPC would be my choice. It also make a fine hunting rifle.

[Outpost75]

AK and M16 platforms have been in service as long in this era as the Brown Bess musket wss in its time.

We can do better now. Not sure what that is, but probably not a metallic cartridge as we know it.

Probably some version of Barry McKaffery's smart guided, precision, semi-auto grenade launcher, next generation beyond the. XM24.......