.223 and an M4

[MarkP]

I was having a discussion with a buddy of mine and the question of an M4A1 rifle having the capability of firing a .223 round effectively and safely arose. I know that there is a slight difference in the outer dimensions between the 5.56x45 and the .223, however, I don't know if that would effect how efficiently the rifle would perform while firing a .223 instead of a 5.56.

 

[average_shooter]

5.56x45mm is the NATO standard, so if you're talking about a real M4 then .223 would be just fine to run through it. It's firing 5.56 in .223-only chambers/barrels that's the problem.

 

[Avenger29]

It's firing 5.56 in .223-only chambers/barrels that's the problem.

Yep. Also you have to watch for some of the...cheaper...manufacturers that claim they have a 5.56mm chamber and stamp it so on the barrel, but the chamber is much closer to or is .223 dimensions. They can get away with it because it usually doesn't cause huge problems, but popped primers, problematic extraction, less tolerance for steel cased ammunition, etc can result.

 

[MarkP]

Yes, I was talking about the genuine m4 rifle the military uses today.

Thanks guys, gave me exactly what I was looking for.

 

[billybobjoe]

The millitary loads their "5.56" version hotter than the "civilian" .223. They use a longer 68 grain bullet that goes a bit faster. This bullet is more unstable and yaws when it hits flesh. As it tumbles to go ass backwards it breaks at the cannalur[sic], squeezes the lead core out, fragments, and does massive damage. The millitary also loads it's 9mm about as hot as a 357. It yaws to and does more damage. This way they can get a full metal jacket bullet to do the most damage. They have to use FMJs by international treaty. A true "5.56" will not have enough head spacing in a .223 marked gun. Don't bet your life on this--I think a box marked "5.56" with say 50 grain bullets would probably be ok in a .223 rifle. MAYBE!!! Ruger Mini 14s can take either.

 

[billybobjoe]

Basically the millitary loads everything hotter. Better safe than sorry and never put the wrong ammo in a gun. Forget what you might do to yourself--YOU MIGHT BUST UP YOUR GUN. SAVE THE GUN!!! Lost my leg, but I saved my Harley.

 

[average_shooter]

Well, the military may load their rounds hotter, but due to that there is also a slight difference in case dimensions between .223 and 5.56. Also, 68 grains is not the only bullet weight used in the military. Stability is determined by a few different factors, not just bullet weight. Bullet weight and barrel twist-rate both come into play when it comes to stability. I think it's also argued about whether or not the bullet is actually designed to tumble, I know I wouldn't count on it.

As an aside, non-expanding hollow-point projectiles are allowed in combat. A friend of mine who went through the Army Designated Rifleman course related to me that they used Black Hills ammo, though I can't recall the bullet weight or barrel twist in the DRM rifles.

 

[rcmodel]

Standard GI issue SS109 NATO/M855 green-tip is 62 grain, not 68 grain.

The older M193 ball is 55 grain FMJ-BT.

Special Ball, Long Range, Mk 262 Mod 0/1 uses a 77 grain bullet.

rc

 

[Radaray]

According to Hornady Fifth Edition Handbook of Cartridge Reloading Vol. 1, the .223 Remington cartridge case and the 5.56mm NATO cartridge case share identical outside dimensions. The only differences I have found is that the military brass has somewhat thicker case walls, thus for the same charge, may produce higher pressures.
The 68 grain bullet has long been the mainstay of the NATO round, but there are other bullets that are used, including the 62 grain pill.
If handloading, it wouldn't make any difference if the case dimensions were not the same, as they would be after resizing anyhow. Personally, I prefer used military brass, as it seems stronger and more durable. Once the crimped primer pockets are taken care of, the brass is good to go.

 

[Mags]

The millitary loads their "5.56" version hotter than the "civilian" .223. They use a longer 68 grain bullet that goes a bit faster. This bullet is more unstable and yaws when it hits flesh. As it tumbles to go ass backwards it breaks at the cannalur[sic], squeezes the lead core out, fragments, and does massive damage. The millitary also loads it's 9mm about as hot as a 357.

What the heck are you talking about? Your whole post is made up. 68 grain military bullets? 9mm nato is as hot as a 357? A 50 grain 5.56 bullet? Come on man don't be posting things like that. 9mm NATO can be safely shot in most modern 9mms and as already pointed out the military uses 62 and 55 grain bullets in its 5.56 rounds. As for the OP many will say you can safely shoot 223 in 5.56 but not the other way around. I disagree and believe 223 in 5.56 and the other way around can be done safely. I have yet to see a damaged rifle from shooting 5.56 in 223 chambers.

 

[cbrgator]

Basically the millitary loads everything hotter. Better safe than sorry and never put the wrong ammo in a gun. Forget what you might do to yourself--YOU MIGHT BUST UP YOUR GUN. SAVE THE GUN!!! Lost my leg, but I saved my Harley.

Actually, commercial .308 is generally hotter than 7.62 NATO.

 

[RockyMtnTactical]

Outwardly, the 5.56 and the .223 are identical. It is the pressure that is different. It is safe to shoot 5.56 in a 5.56 chamber, but not in a .223 chamber. It is safe to fire .223 in a .223 or 5.56 chamber.

 

[gb0399]

I've shot commercial .223, nato 5.56 green tip (62gr), nato 55gr fmj, 77gr BHA long range and 42 gr frangible all from an issue M4A1. It will shoot them all with out worry. However ensure that you are using the heavy barrel to fire the 77gr

 

[mljdeckard]

You were shooting commercial ammo in a .gov weapon?

 

[gb0399]

yep

If the government buys it then its gov property.

Some training sites don't allow green tip on their ranges the steel core destroys taretry, and 55 grain is not always available

 

[taliv]

wow, lot of bad info in this thread.

thanks rcmodel, mags and rockymtntactical for correcting most of it, though mags, just because you haven't personally seen a kaboom, doesn't mean it's safe.

gb0399, why do you need a heavy barrel for the 77? It shoots fine in any 5.56nato chamber.

 

[gb0399]

you could shoot it out of any AR, but I wouldn't. The M4A1 is a fully automatic rifle. With the origianal barrel, shooting on full auto, the barrels were rupturing. A second barrel came out that is considerably thicker. the issue was with 77 gr. So... while the problem was occuring during automatic fire I would still not fire it trough a standard diameter barrel even on semi.

 

[HorseSoldier]

The 68 grain bullet has long been the mainstay of the NATO round, but there are other bullets that are used, including the 62 grain pill.

What other people have already said -- SS109/M855 uses a 62 grain bullet. Unless something has been introduced for the cool kids since I got out last year, there's no 68 grain ammo in the system (or in use by anyone else in NATO, as far as I know).

 

[Mags]

You are correct Taliv I should not reccomend to others to shoot 5.56 in their 223 rifles. I just can't seem to find any documented proof of a major failure or dangerous condition in doing so. However what works for me should not always be reccomended to others.

 

[Boba Fett]

@ The Real Mags

http://www.thegunzone.com/556v223.html

Almost a quarter of a century ago, SAAMI recognized potential problems with shooters assuming that the 5.56mm cartridge was identical to the commercially available .223 Remington round. Here is their 31 January 1979 release, with some minor errors corrected:

With the appearance of full metal jacket military 5.56 ammunition on the commercial Market, it has come to the attention of the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) that the use of military 5.56mm ammunition in sporting rifles chambered for Caliber .223 Remington cartridges can lead to higher-than-normal chamber pressures and possible hazards for the firearm, its user and bystanders.

Tests have confirmed that chamber pressures in a sporting rifle may be significantly higher in the same gun when using military 5.56mm ammunition rather than commercially loaded Caliber .223 Remington cartridges, according to SAAMI.

SAAMI points out that chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber.

SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer.


Additionally, SAAMI's Unsafe Arms and Ammunition Combinations Technical Data Sheet page states:

The .223 Remington is rated for a maximum of 50,000 CUP while the 5.56mm is rated for 60,000 CUP. That extra 10,000 CUP is likely sufficient to cause a failure in a chamber that's only rated for the "sporting" .223 Remington.

 

[vanfunk]

wow, lot of bad info in this thread.

You said it, Taliv!

the issue was with 77 gr. So...

The issues with barrels rupturing had everything to do with rate of fire, and nothing to do with bullet weight or type.

while the problem was occuring during automatic fire I would still not fire it trough a standard diameter barrel even on semi.

You are certainly entitled to your opinion, but just for the sake of others who might be reading this thread, there is absolutely no risk in firing 77 grain ammo in a standard Government-weight M4 barrel.



vanfunk

 

[gb0399]

As with any firearm, I would only suggest using ammunition recommended by the manufacturer. Colt only recommends using M855 (62gr) and M193 (55gr) in the M4A1. (see link below) Every one is entitled to their opinion, and it is the opinion of USSOCOM that the 77 gr bullet is not safe for the M4 or the user when fired through the original "standard" barrel. I'll dig up the safety message and post it next week.

http://www.coltsmfg.com/publications.aspx

 

[Mags]

Yes Boba, I am aware of the higher chamber pressures between 223 and 5.56 I just have never seen any documented kabooms in an AR from shooting 5.56 in a 223 chamber. I am aware of some bolt action kabooms but none in the AR platform.

 

[X-Rap]

As far as I know the bulk of guns chambered for 223 are bolts which would seem to have a stronger bolt and chamber than any auto/semiauto that is chambered 5.56.
I have never had any issue firing 5.56 through my Savage bolt and they have by no means a robust bolt.
I would have some pressure concerns if shooting hot mil.spec ammo in a semi not rated for such than a bolt.

 

[HorseSoldier]

You are certainly entitled to your opinion, but just for the sake of others who might be reading this thread, there is absolutely no risk in firing 77 grain ammo in a standard Government-weight M4 barrel.

+1. From personal experience running a few thousand rounds of Mk262 through an M4A1, I can pretty emphatically say that if there's a problem it's a pretty rare one. I've never personally had, or seen, a failure relating to 77 grain ammo. I have seen a bunch of failures relating to green tip, but almost all of those related to a bad lot of ammo my unit was issued in summer '06 or so.

Every one is entitled to their opinion, and it is the opinion of USSOCOM that the 77 gr bullet is not safe for the M4 or the user when fired through the original "standard" barrel. I'll dig up the safety message and post it next week.

I'd be curious to know more about this. There was no USASOC or SOCOM warning about using Mk 262 in M4A1s up until end of FY08, as I definitely would have known about it. If it's been issued since then, I'd be interested in knowing what kind of issues they were having. We primarily used our issued 262 with SPRs, but also ran a lot of it through M4s since it didn't tear up steel at close range the same way 855 does.