Ian McCollum tackles an important and long-debated question among AR-15 owners: Can you run .223 Remington and 5.56 NATO ammo interchangeably without any problems?
Short answer: Yes!
Plus he clears up a little bit of misunderstanding about “military grade” ammo.
Tags: 5.56 NATO, AR-15, Guns, Ian McCollum, video
Just two comments about the video…
– He doesn’t mention the .223 Wylde chambers that are available to optimize performance with both .223 and 5.56. It probably only matter to precision shooters (varminters mostly), but it’s out there.
– The is a big difference between WWII ammo produced for the M1 Garand and commercial ammo now made for the .30-06. I’ve talked with a lot of high-power competitors who used to use the .30-06 in accurized Garands that told me they had personally experienced bent op-rods when firing commercial ammo in the M1. That made hunting with a Garand essentially impossible because all of the mil-spec ammo was FMJ (or AP). Bunch of years ago Hornady finally came out with a 150-grain soft-point hunting ammo specifically designed for use in the M1…although I’ve done it personally, hauling a Garand through the woods is a bit of a pain, and I had to buy the special 5-round en-bloc clips for it to meet the state regulations.
Again, just picking some nits that I’m sure he ran out of time to address.
The only thing I can add to this is from personal experience with my old Mini-14. it will shoot both rounds. However, the 5.56 rounds tend to lock up the action. The rifle required a solid thump to open the bolt and extract the 5.56 cases. This is never an issue with the.223.
So I only shoot 223 out of that rifle.
Ian covers a lot of the issues, but like all of these things, you can’t answer everything or address everything even in a lengthy YouTube video.
Military ammunition, for example: It ain’t created the same, even if it all meets NATO specification. Ask me how I know…
Oh, fine, I’ll tell you…
Picture me, as a rather ancient squad leader back during the early 1990s. Also, picture me with the opportunity to do cross-training with some British troops of a weekend, with a metric butt-ton of their ammo. Also, visualize me having access to the unit arms room, and a willingness to help said Brits navigate the intricacies of getting a range open and operable on Fort Lewis.
See, I wanted to get my grubbies on some of those SA-80s, and fire them extensively. I’d heard so much about them…
End of the day, I learned a couple of things: One, the only worthwhile bit of kit on that SA80 was the sling, and that British Army Radway Green 5.56mm NATO was emphatically not something you want to fire through an M16. Ever.
I’d scrounged up some US Army-specification ammo that was M855 equivalent, and we ran some through the SA-80s that were on offer. We also ran Radway Green ammo through the M16A2s and the M249 SAW that I’d brought from our arms room for the Brits to familiarize themselves with.
Upshot? British Army Radway Green ammo was filthy, utterly filthy. Two magazines of that crap through one of our M16A2s, and the carbon was thick enough that you were seeing an observable degradation in performance, along with very sluggish operation. Same with the M249, but not as bad.
Our ammo in the SA-80? Ran much cleaner than theirs, but the velocity and bolt thrust were observably a lot higher; I speculate that our powders produced much higher and different pressure profiles than the Radway Green ammo did, which was optimized for the AR-18 pattern gas system with the short-stroke piston.
No military ammo load is really cross-compatible. Even the German 7.62 NATO of yore was observably different, being loaded for the G3 and the MG3. You tried running either through an M60 or an M14, you were going to be hating life. I watched a friend of mine break a bolt on an M1A with German ammo that was delinked off of what they meant for the MG3.
That little cross-in-circle is oftentimes a liar; every time you use something from somewhere else, whether or not it is “military grade”, you need to bear in mind that the arsenal that produced it was loading for their specific weapons set, and that even minute differences between weapons will produce far different optimization curves for their ideal loads.
Hell, look at how long it took before they paid attention to the issues of the M855 loaded for the M16A2 vs. the load they really needed for the M4. That took from around 1990 to 2007-ish before they finally got off their asses and did the necessary testing, followed by development of the M855A1 loading.
So… Yeah. Ian covered the basics, but there is still a hell of a lot more to it than he covered.
Kirk,
Interesting how things keep happening again and again. The issues with the early M-16 in Vietnam were due to ammo specs being changed….
In my library I have the Collector Grade book The Last Enfield by Steve Raw. He was a Royal Marine armorer, and the book is a fascinating history of the L-85/SA-80. It has since been surpassed by the book by Johnathan Ferguson (who has the coolest gun related job title ever! “Keeper of Arms and Artillery” for the Royal Armouries), ironically published by Ian’s publishing company!
In it, Steve Raw has a chapter about the attempts to fix the many issues with the S.A.W. version of the weapon, the so called L.S.W (Light Support Weapon).
One of the proposals was to issue BETA C 100 round drum magazines to increase fire sustainability. The company was loaned a couple of weapons for testing and development. They had issues. The mags worked fine initially, but started to have problems with the last 15 or so rounds. BETA did extensive testing, and found that there was no problem when using US or other NATO ammo, but that the Radway Green ammo produced a lower port pressure and thus the system lacked sufficient kinetic energy to overcome the increased stripping pressure of those last 15 rounds.
On the subject of 5.56/.223, the same applies to 7.62 NATO/.308. The military cartridge has the exact same external dimensions, but the walls are a bit thicker and so internal volume/capacity a tiny bit lower. The chamber dimensions are the same, but the leade/throat dimensions are a bit different. In theory, this can cause a pressure difference. In practice, it is well within the engineering tolerances of pretty much any rifle, so the rounds are interchangeable in practice, unless you are hand-loading and using oddball bullet weights and so on.
Interestingly, U.S. S.A.A.M.I. specifications differentiate between NATO vs. commercial cartridges, but the equivalent European C.I.P. standard does not, and in Europe they are considered completely interchangeable.
Bollocks! There’s a reason for the distinction. If you have a Contender with a factory .223 Remington barrel and put a typical 55 grain 5.56mm ball ammo round in it you will be using force to close the action. That’s a clue you shouldn’t fire that round in that gun. It’s about ‘leade’. Yeah, you can muscle a .223 marked Mini-14 to accept it but you’ll be damaging the Contender’s lock lugs.
@ Paul,
Yeah, the idiocies keep repeating. It’s mind-boggling, when you go back and look.
Circa 1967, they had a new issue of OG107 jungle fatigues, which were notorious for having “issues” with the crotches. They weren’t very well-made, and they usually left your balls hanging out in the jungle in pretty short order. They eventually had to redesign the uniform to make a much stronger crotch that wouldn’t tear out after limited use.
I saw some of those uniforms that got dug out of stores when the Army was trying to run down its stocks of the OG107 in the early 1980s, along with the fixed ones. We were authorized those uniforms for a few years while they ran through them, and you could see the marked difference between the older versions and the later ones. Lousy design, to be very honest.
Flash forward a few years, when they were issuing the Hot Weather BDU in the same ripstop fabric. First ones I saw, what did I see? The selfsame crappy initial design of the OG107 crotches, repeated yet again. Same issues manifested, same fix: New, reinforced heavier-duty crotches.
OK, I thought… Not a big deal; someone forgot.
However, when they issued the new ACU, what did you see repeated, yet again? Oh, gee… Same lousy design of crotch. Which failed miserably, leaving guys with their nuts hanging out not alone in the jungle, but out in the public spaces of a Middle-Eastern Islamic nation. Again, second version of the uniform had to be issued…
These idiots leave me despairing at their inability to learn. You would think that there’d be a “Lessons Learned” file regarding uniform design at Natick, but… Apparently not.
I remain dubious of the proposition that any alien will ever find truly intelligent life here on earth, even if we are around when they arrive, and haven’t exterminated ourselves.
By and large the BDUs suck in hot, wet weather. And a BDU with the Navy’s ridiculous (now retired) blue ‘cammie’ pattern? Oy!
I got to avoid the deficiencies of the BDU uniform when assigned to the Navy support command post at NAS N’awlins for Katrina recovery. As I was an NFO, I took 2 flight suits, 4 tees, 4 gym trunks, and 4 pair white socks. There was always a flight suit, tee, gym trunk and 1 pair of socks drying in my hooch and I had something clean to wear every day. I substituted black ‘jungle boots’ for flight boots, no one noticed that mattered. It was a functioning work outfit.
The ‘shoes’ in the CP and the poor Marines wading through the sewage every day … hmmm, not so much.
“I’ve talked with a lot of high-power competitors who used to use the .30-06 in accurized Garands that told me they had personally experienced bent op-rods when firing commercial ammo in the M1. That made hunting with a Garand essentially impossible because all of the mil-spec ammo was FMJ (or AP).”
The problem with M1 Garands and .30-06 is not with the chamber specs, but with the gas operating system. It was designed specifically to operate with the military .30 caliber ammo of the time. Most civilian .30-06 rifles are bolt action so this is not an issue.
This was well understood when I was shooting with the Navy Marksmanship Team back in the ’80’s and ’90’s so high powered shooters who bent their op rods using higher pressure ammo apparently weren’t overly experienced.
For hunters who want to use commercial ammo in a Garand, the fix is very simple: install an adjustable gas plug. Inexpensive, doesn’t permanently alter the rifle, and after adjusting, can shoot any commercially available .30-06 load.
Or just load your own…which is what I do.
Regarding the 5.56 vs .223 thing: I note that the speaker in the video hedged his bets. He didn’t say it’s impossible for a .223 chambered rifle to blow up with 5.56 ammo, he just said he’s never heard of it happening, he’s never had any problems and it’s unlikely. Which is pretty much what I’ve always heard as well. But to my mind, that’s not the question. Engineering standards dictate that chambers are going to be able to withstand higher pressures than the maximum rated without a catastrophic failure, but what will those higher pressures do to the rifle over time?
Especially with a carbine length gas system on a 16″ barrel which is fairly common in civilian rifles. They’re already creating more pressure in the gas system than is probably healthy for the rifle…is adding to that a good idea?
Of course, an adjustable gas block would alleviate that issue as well, so that’s what I’d suggest. Better safe than sorry in my humble opinion.
“If you have a Contender with a factory .223 Remington barrel and put a typical 55 grain 5.56mm ball ammo round in it you will be using force to close the action. That’s a clue you shouldn’t fire that round in that gun. It’s about ‘leade’.”
I don’t have a Contender, but aren’t they built with accuracy in mind? If so, I’d imagine the chambers are reamed with much tighter tolerances than an AR platform. The video didn’t claim that the ammo is the same, only that, in his opinion, it’s interchangeable in the AR platform.
I don’t completely agree with him, but that was his point as I took it.
I am by no means a Garand expert, but I recall talking about that “commercial ammo” issue with a guy who absolutely was.
His contention was, and I can see the sense of it, that the issue with the Garand bending its operating rods stemmed primarily from the vastly different pressure curves observed between the old-school WWII-era ammo and anything modern.
The older powders generated their gasses more slowly, and did not produce the short, sharp shock to the op rod that he felt created most of the bending issues. Since he spent a lot of time handloading and working up loads, I think his testimony may have some validity. The way he put it, even if you overloaded the cases with the older, slower-burning powders, they didn’t do what the modern, faster-burning ones did.
As with high explosives and the vastly different effects you get from them based on the rate of detonation and the amount of gasses they generate, so too with the lower explosives we use as propellants. What works wonderfully well properly placed in a specific application doesn’t work at all, in another.
Ammo is something of a black art; there are things I’ve personally experienced with aged-out or improperly stored ammunition that would scare the ever-loving crap out of you. Sometimes the propellant decays one way, sometimes another. It will even differ in between cartridges in the same lot, based on some entirely arcane and unknowable factor. Which could just be down to a few degrees difference in temperature stemming from it being stored deeper in the container.
I had the questionable “fun” of dealing with what the loggies call a “frustrated cargo” ammunition container. It never should have gone where it went, and since it got lost in the system, it spent at least 18-24 months stuck in Kuwaiti customs and some other cargo holding areas. The ammo that came out of that container? Hoooooo boy… The Ammuntion Quality Assurance and Surveillance bubbas were hating life, because some idiot had unloaded that crap into the system without checking with them. The supposition was, because the ammo performance was all over the chart, that there had been differing amounts of degradation in ammo that was even on the same pallet, based on the thermal penetration and how much it had cycled between hot and cold in the unprotected heat of a Kuwaiti desert environment. Stuff that was on the exterior of the pallet would have undergone faster heating and cooling to more extreme temperatures than the stuff deeper in the stack, and even though it started out the same lot with the same characteristics, some of it fired super-hot, and some of it was squibs. Because some genius hadn’t gotten the QASAS guys involved in checking it, the ammo got out into the system and then they had to chase all of it down, which wasn’t exactly easy.
Some ammo is temperature-sensitive. Some isn’t, and even the minute variations in between accepted lots that test out precisely the same with regards to what they left the factory as, the insults experienced on their way to the firing line can produce massively different results. Some stuff they had was supposed to be specifically designed to be less temperature-sensitive, and it was actually more, in practice. Meanwhile, some things that they didn’t pay the extra money on were rock-solid, and nothing done to them ever made them perform at all differently than they were initially designed to.
Ya leave stuff in hot places? Be careful, and expect weirdnesses to appear.
I still stand by what I (and Ian) said. In most rifles the two cartridges will interchange safely. Thomson Contenders are specialized, so I am not that surprised that the leade is tight, being as they are for specialized target use, either handgun hunting, metallic silhouette shooting and so on.
That said, as there IS a difference in the throat/leade, and problems can occur. The .223 Wilde chamber would not be a thing otherwise. For those concerned about it, the rule of thumb is that commercial ammo can always be fired from NATO chambers, the issues comes when firing NATO ammo in commercial chambers.
RE the Garand. I was under the impression that the issue was with heavy bullet hunting and target loads. The fixed gas system being optimized specifically for the milspec cartridge, and a 150 grain bullet. Put a heavy 180+ grain hunting bullet in, and the pressure curve will be very different. Clearly, my impression was wrong. An experienced competition shooter who loads his own (Kirk’s source), would certainly know, and if he says it is modern powders, I would have to agree. It makes sense, especially given the Early M-16’s issues AND the British L-85 rifle’s issues.
M-16/M-4 works fine now, but the issue was solved by modifying the rifle to tolerate the new powder, not by going back to the old style powder. The new buffers being the fix that worked. The cyclic rate on a modern AR platform rifle is 700-850, vs the original at around 600-650, a result of higher port pressure with the spherical ball powder.
I imagine that even with the gas port so near the muzzle, a Garand will still have higher port pressure with modern ball powder than older IMR style stuff. IIRC, the British ammo used older style flake/stick propellant, and so a lower port pressure than most other NATO ammo which uses modern spherical ball type powder, which accounts for it working better with non-British ammo.
Considering so many AR15 “amateur” builds, I’d make sure chamber/bolt headspace is correct. Go/No Go gauges aren’t expensive or have a real gunsmith check it.
[…] ANSWERING THE IMPORTANT QUESTIONS: Can You Run .223 And 5.56 NATO Interchangeably? […]