Ryan asks:
Hello, After reading the reviews on the Smith & Wesson MP-15 from your site, I went and got one. I was torn on which make and model to buy. But your reviews and other info I got sealed the deal. I have one question concerning ammo. I was always under the impression, that what ever was stamped on the barrel was the only caliber to be fired through the gun. Mine is clearly stamped Nato 5.56 there is no stamping that it can fire 223. I was told when I bought it, that it can fire both 5.56 & 223. I hear different tales on what is right and or wrong. Please help clear the air for me.
Believe it or not, I get this question a lot. So let me lay it out for you . . .
All ammunition is produced to a given specification, which describes everything from the case dimensions to how far the bullet needs to be seated in the case neck. But the most important of these specifications is the maximum chamber pressure metric.
Barrels, bolts and other components are designed to contain the pressure from the expanding gasses in the cartridge as the gun goes off, but they are only designed to withstand a certain level of force. If the pressure in the chamber exceeds the design limits, the parts can shear or rupture. In other words, the gun explodes. Allow me to illustrate:
Yeah, not pretty. It was a nice Cav Arms lower too.
Anyway, in order to keep everyone on the same page and make sure that the parts can handle the load, manufacturers use a set of common specifications. Unfortunately, thanks to the military there are two different standards for the AR-15’s standard cartridge. And they’re measured differently, too.
In the beginning, there was the .223 Remington cartridge which was a version of the .222 Remington cartridge tweaked to work in the AR-15 design. Then the military took it and jimmied the specifications a little further to make it suit their needs. Since the .223 Remington cartridge was already in civilian use and registered with the civilian specification authority (SAAMI), it was stuck and wasn’t able to be changed to match the military specification when it came out. The two major changes between .223 Rem and 5.56 NATO are that the throat length is longer and the chamber pressure is measured differently.
“Throat length” is defined as the distance between the end of the cartridge neck and the point at which the rifling in the barrel engages the bullet. In the above image the throat length is clearly identified as the green markings on the bullet and marked as (a) on the barrel.
A longer throat length will allow you to load a heavier bullet (since length is the only way to increase weight with a fixed diameter projectile and using the same materials), which are more accurate at long distances and such. But with lighter bullets, a longer throat means that the bullet will not engage the rifling as quickly as desired and may lead to concentricity errors as the bullet wobbles off center before hitting the rifling. That’s a bad thing, and negatively impacts accuracy.
A shorter throat length means lighter bullets are more accurate. But if you try to load a longer bullet, the short throat length will push the bullet further into the case which increases chamber pressure and can lead to explosions and other bad things.
So, in short, longer is better. And 5.56 NATO is longer.
Speaking of chamber pressure, that’s the other thing that changed. The NATO maximum chamber pressure is 12% higher than the SAAMI .223 Remington maximum chamber pressure. However, due to the way in which those chamber pressures are measured (NATO measures at the throat, SAAMI does not) the pressures aren’t exactly the same. Nevertheless, the common belief is that 5.56 NATO pressures are higher than .223 Remington pressures.
Due to the difference in throat length and chamber pressure, the conventional wisdom is that .223 Remington ammo is safe to fire through a 5.56 NATO gun, but not necessarily the other way around. But due to the different throat length, the .223 Remington ammunition won’t be as accurate.
There is, however, a compromise. The .223 Wylde chamber that is used in most National Match AR-15 rifles is designed to combine the best of both specifications and work for either caliber. I believe it also has a longer throat than either spec, which means that you can use longer bullets than anything else. But again, longer throat can lead to concentricity issues.
In my experience, after years of not caring and firing both through either barrel, I get the feeling that in the end it really doesn’t matter. Even so, I try to always buy 5.56 NATO barrels.
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Thanks for telling a good story and keeping the numbers light, Bruce. They get a bit hard to wade through after a while. These windbags need new jobs.
Probably an economy grade shotgun with a Western name. New from Ruger, the Saguaro!
I hate to keep trolling, but it’s becomming a personal campagin to me. I read the article, and just about the time I get ready to comment you sneak one of those annoying AUTO PLAY video advertisments on me. PLEASE, PLEASE, PLEASE…can someone turn them off? Or at least give ME the option to turn them off…:(
Obviously, if your shoes are untied you are unfit to carry a gun. The grabbers will play games till its too costly to play games, like deputy dog there, Randy
One of the funniest things I’ve run across at the Modern Firearms and Ammunition site is the new (introduced 2006 or so) 9mm police revolver used by cops in the People’s Republic of China. Butt-ugly side-swing DA fixed-sight job (looks like a cheap copy of an Armscorp .38, with a thumb safety) chambered for what is basically the old 720-fps .38 S&W. The thinking being is that if the only place to get a gun is to steal it from the cops, let’s give the cops guns that won’t penetrate police body armor. Ah, so…..
I’m with Betsy. We should also have some amped-up, truly graphic, hyperviolent rape and sodomy scenes with nothing held back showing women of all ages being horribly beaten and savagely subjugated. Because, after all, we don’t want to silence the screams.
What’s that, Betsy? I can’t hear you.
There could also be an issue with both the .223 and 5.56 Hornady Superformance rounds when fired from carbine/mid length gas operated rifles. Case deformation and blown primers should be monitored when firing those combinations. I found the page in an obscure non-linked place in the Hornady website:
http://www.hornady.com/ammunition/superformance-in-gas-operated-firearms
Looks to me as if the Senator suddenly grasped the level of resistance the Minnesota legislature was up against. Don’t bang on closed doors.
I’m glad they pulled it, but need to make sure they don’t try to put it back into play later. I live in WI, but I’ve been thinking of moving to MN. Been making sure to write reps over there, and keep on my friends in MN to contact their reps.
So take cover, wait for the reload allowing the bad guy to kill or wound as many as he can, then attack? Got it.
*Sarcasm Off**
ETA: If in a school will any pen or pencil do or does it have to be a #2?
Interesting that it takes a 100+ cops – many with full-auto “assault” weapons with those evil “large cap mags”- to deal with one nut but I’m supposed to deal with any number of bad guys with a bic.
One little fact he left out: in the Gifford shooting, the gun malfunctioned during the reload and the idiot didn’t know how to fix it fast. That gave people time to jump him.
They can point out a few random accidents here and there, but I’m guessing the majority of these “children” injured are non-white and gang affiliated.
You want to stop a massive percentage of “gun deaths” in the USA? Deal with the drug problem in an effective way.
Compare 771 deaths and injuries to 260 million plus murders at the hands of government between 1900-2000. If history doesn’t show you that government requires checks and balances, then you are not paying attention.
http://www.hawaii.edu/powerkills/20TH.HTM
These rounds may or not be “evil” or “powerful”. but here in New Zealand, the hunting guidelines strongly suggest against using anything less than .243 on our big, tough deer.
Only goats or wallabies are suitable game for the .223/5.56 calibre rounds.
I like math. So there were 771 “children” killed or injured by firearms in 10 years cared for by Children’s hospital in St. Louis. And 35% of those were under age 15. So that means 270 “little” kids were killed or injured in 10 years, or 27 a year. I’d like to know how many were killed and how many were injured? And what percentage were justified shoots, i.e. a 15 year old shot to death or injury by LEO to protect the rest of the citizenry? And how many were shot by what the media calls an assault rifle, so we can calculate how many lives will be saved by banning assault rifles (most likey a small fraction of one kid per year).
> Is it possible that Lanza reckoned that killing little children
> en masse would be the final act that would bring gun-control to the fore
Why was this even published?
Those that live off fear, need you to be uneducated, afraid and unarmed.
An irrational person, an irrational act, and thus follows an irrational motivation for that act.
Do not waste your time trying to empathize with a mass murderer. You are searching for answers, but the only answer is that his motivations cannot be understood by a sane mind.
I wonder how many sets were sold…
These look remarkably like L5 AWMs…
For my fellow Coloradoans- Pro Gun Rally at the State Capitol, this Saturday, Feb 23 from 11-1 pm. See you there! Facebook.com/coloradorevolution
So the title says mayorS. So who are the others?
Huge fan of the site, but…
Guys, PLEASE, use spell check, or grammar check or whatever….
“Just about everything about the Mayors Against Illegal Guns organization is designed to be deceive.”……
“designed to be deceive” ???!!!
It just makes ‘us’ look bad and happens too often for the #1 firearms blog in the U.S.A.
I’m not trying to be a ” grammar nazi”, but I forward this stuff to hundreds of my “libtard” friends- and I’m sure many others do too.
It just looks careless and gives them more ammo about how “dumb and backwards” pro gun people are.
Sorry to complain, HUGE fan, keep up the good work.
mp
Yes, having two unidentified sources of audio playing over the embedded YouTube feed I was watching about drove me nuts – yes that actually happened!
This is probably the best article I have read thus far on the differences between the two rounds. Very informative. The picture says it all.
Does anyone have a considered view on the plausibility of an M4 with a high capacity .223 magazine having been used at the Sandy Hook school, given the overall report of:
a) the young lad having carried the Bushmaster around with two other hand weapons, and
b) firing 2-5 rounds into each of 26 victims within 7 minutes and
c) with no professional training at ranges, only the odd trip to target practice with his mum and written & online manuals, and
d) the coroner describing “This type of weapon is not, uh … the bullets are designed in such a fashion that the energy—this is very clinical. I shouldn’t be saying this. But the energy is deposited in the tissue so the bullet stays in [the tissue].”
e) State police Lt Paul Vance said one person suffered an injury and survived, indicating that Lanza was unusually accurate or methodical in his fire – or that most of his victims were shot at point-blank range.
For those of us with little experience with these rifles, do you have any calm & thoughtful comments on how cohesive these descriptions are please? Or are there important discrepancies on what this weapon and ammo are capable of? Thanks in advance.
Corrections and additions to the above posting about the Sandy Hook school incident:
– the rounds were 556 NATO marked “S&B 60 5.56 X 45”, not .223’s
– the murder weapon was a Bushmaster XM15-E2S, not an M4 (oops)
The police report is available at “www.ct.gov/csao/cwp/view.asp?q=535784” and some interesting points from it are summarised below which you guys may have some insights into:
– 5 rounds escaped Classroom 10 hitting 3 civilian cars parked outside.
– the shooter delivered all 153 round in 6 minutes before suicide.
– the shooter was strongly Aspergic, 6ft tall and weighed only 112pounds. He carried in ammo & 3 guns weighing 30½ pounds in total, ie. 27½% of his body weight.
– of the eight PMAG30’s used, 3 live rounds “fell” out onto the floor, and one more live round “fell” out into his pocket. Is this a common failure ?
– Each of two classrooms had 2 adults and 16 children. In the first the shooter expends 4 rounds/victim and 1 escapes, then in the second (final) classroom he expends 7 rounds/victim and 11 escape. This could just be nerves, as sixty seconds after the first police car arrives, he commits suicide. The shooter wore earplugs throughout.
I’m still not convinced Sandy Hook even happened. There’s just too much evidence out there that contradicts the event. My favorite is the video of one of the “dads” who doesn’t realize he’s being recorded, and he’s all chipper, laughing, excited right before a press conference. As soon as he’s ready to walk to the podium, he immediately gets into character, somber, tries to bring up some tears and a sad face.
It may have happened. I just don’t put it past our governments to fake something like that. There were only a few people who actually went into the school, and of course even the photos of the school didn’t match other photos. Photos on the school website showed different school colors from those taken by the person inside. Photos outside the school captured by Google Maps didn’t match those captured by helicopters flying over the scene. Helicopter video shows the exact same people walking in circles not much different than the extras in The Truman Show. Helicopter video also showed handicap spaces not maintained, fire exits clearly blocked by boxes and supplies, which supports the reports that the school had been closed several years before. Internet caching didn’t match a school that was being used. There was NO internet activity in the building for several years prior to the event. Facebook pages of some of the victims were amazingly created just a day or two before the event. I’m bored. Do your own research.
Jeremiah in Colorado, Thank you!
http://www.cluesforum.com
scroll down to: “London, Madrid, Oslo and other faked terror events: the psyops are everywhere”
Jeremiah in Colorado, Thank you!
http://www.cluesforum.info
scroll down to: “London, Madrid, Oslo and other faked terror events: the psyops are everywhere”
They should pack up and move their tax revenue generating business out of that hellhole.