223 remington verses .556

[USMC87]

I have had several people come to me and say that you can not shoot 556 in a rifle marked 223 rem, I can not find any difference in my test. Your help is appreciated.

[pcolapaddler]

A quick Google search will return a number of links detailing why your shouldn't use 5.56 ammo in a .223 firearm.

Here are a couple

http://forum.gon.com/threads/no-no-h...of-223.779291/

https://thesportsmansshop.com/223-vs...mo-comparison/




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[rancher1913]

the shoulders are just a little different and 5.56 is usually a hotter round. 223 can be used in 5.56 but if you go the other way you could have problems, thats not to say its not done, but its a good possibility that some of those blown up ar's were 223 that people fired 5.56 out of.

[NyFirefighter357]

It also depends on the gun, although Ruger Mini-14's are stamped 223 Rem. Ruger says it is O.K, to shoot 5.56 in all the Mini-14's with the exception of the Mini-14 Target Rifle

[BK7saum]

It has nothing to do with the case or chamber body. Cases and chamber body dimensions are for practical purposes identical

5.56 is loaded to higher pressures and the bullets loaded in military ammunition may be and are loaded to fit a longer military throat.

When 5.56 ammuniition is fired in a .223 rem chamber, the bullets may be jammed into the lands and the pressures will further elevated.

That is why the rule exists not to shoot 5.56 ammunition in a 223 chamber, it has to do with throat and distance to ogive being longer in the 5.56 chamber/ammunition.

The fix, if you will, is to shoot a 223 wylde chamber which has a somewhat longer throat that the 223 and can accommodate the military ammunition.

[Texas by God]

I don’t recall any mention or warnings of this in any loading manuals or gun magazines until the 1990s or so. We fired quite a bit of 5.56 milsurp ammo through my brothers Remington 700 and Ruger #3 and my Mini 14 back in the 1970s and 1980s with no drama. Ammo from several different countries. Maybe we were just lucky.

[tomme boy]

Shoot about 1500 rounds through a 223 and then you have a 556. Most of the older guns I had back in the 80's and 90's had LONG throats. It wasn't till bullet advancement in quality was out pacing the gun manufacturers sub par guns that the manufacturers had to catch up. That's why they were not marked as a 556. I had a Henry bull barrel in 223 that a flat base 55gr bullet would not touch the lands no matter how far it stuck out.

It used to be you had to spend several thousands of $$$ to get a gun to shoot 1" or less. Now most $200 walmart guns will do that.

[Larry Gibson]

I don’t recall any mention or warnings of this in any loading manuals or gun magazines until the 1990s or so. We fired quite a bit of 5.56 milsurp ammo through my brothers Remington 700 and Ruger #3 and my Mini 14 back in the 1970s and 1980s with no drama. Ammo from several different countries. Maybe we were just lucky.

The "warnings" [actually were cautions] came about in that time period not because of any inherent danger of pressure but simply because the "newer" 5.56 M855 had a longer 62 gr FMJBT bullet and would not stabilize in the 12" twists of most "223 Remington" chambered bolt actions, single shots and ARs of the time period. It was the internet experts [several comment on the topic in the above listed sites] who came up with the pressure BS.

The 223 Remington factory ammunition and newer load data [of the last 20 +/- years] is held to ANSI/SAAMI standard with a MAP of 56,000 psi. US made M193 for the military adheres to NATO/STANAG specification. CIP [European standards] PMAP for 5.56 is 62,366 psi. Various lots of M193 [LC, TW, WCC from the '70s through 2000) have tested at 53,700 psi to 60,500 psi in the Contender test barrel. Several lots of M855 [SS109 and "Green Tip"] have tested at 58,700 to 62,300 psi in the same tight chambered "223 Remington" test barrel.

I have shot thousands of 5.56 {US M193 ball} through different rifles with 12" twists having "223 Remington" chambers and marked for such w/o a single indication of pressure problems. I also have pressure tested numerous lots of M193 in a "223 Remington" Contender carbine barrel. None of which showed any pressure problems. There was one lot of commercial Winchester 5.56 did give a high psi measurement [above 62,300 psi] but it was still within in NATO/Stanag specifications.

Bottom line is with modern action rifle having "223 Remington" chambers you can shoot all the US made M193 you want w/o any fear "over pressure" if the barrel twist is 12" or faster. Accuracy out of barrel twists slower than 12" can be iffy if existent at all. With rifles having barrel twists slower than 10" shooting US made M855 "green tip" is not advisable simple because accuracy will be poor with bullets keyhole as quick at 25 yards. This includes bolt actions, single shots and gas guns. Of course any such rifle marked "5.56" can use ammo of both 223 and 5.56 variety except that with 7 - 9" twist barrels some thin jacketed bullets may spin apart in flight with velocities above 2800 fps.

[remy3424]

It has nothing to do with the case or chamber body. Cases and chamber body dimensions are for practical purposes identical

5.56 is loaded to higher pressures and the bullets loaded in military ammunition may be and are loaded to fit a longer military throat.

When 5.56 ammuniition is fired in a .223 rem chamber, the bullets may be jammed into the lands and the pressures will further elevated.

That is why the rule exists not to shoot 5.56 ammunition in a 223 chamber, it has to do with throat and distance to ogive being longer in the 5.56 chamber/ammunition.

The fix, if you will, is to shoot a 223 wylde chamber which has a somewhat longer throat that the 223 and can accommodate the military ammunition.

I agree with BK7. There is a lot of misinformation out there, even here. The inside capacity of the intended cases likely vary more than the outside (wall construction on the 5.56 designed cased). Should be of a little concern when reloading them, not enough to be an issue for me. More of the difference is the chambers/leade oif the firearm and the bullets of the loaded ammo. Guessing modern firearms could deal with the 5.56 additional pressure if the bullet is not lodged into the rifling. Larry nails the accuracy issues with barrel twists and the longer bullets asscoiated with 5.56, but a lot of 223 Rem barrels have fast twists today.

[Lloyd Smale]

Im with larry. Ive been shooting them interchangeably for my whole life and never once had a problem doing it either way. Just one of those topics that wanabe gun experts like to post about to make themselves look knowledgeable.

[USMC87]

I really appreciate the comments and help guys.

[Vopie]

I have to laugh every time this comes up! Whenever I'm asked I pull out a couple G.I. issued, Colt made, 20 rd. mags that came home with me many years ago, they are stamped .223!

[1hole]

I have had several people come to me and say that you can not shoot 556 in a rifle marked 223 rem...

"Can't" is a big word there; you surely can or it wouldn't be a hazard because it wouldn't be possible. The right word is "shouldn't" because the 5.56 is something of a "Plus P" round and most .223 rifles aren't proofed for that level of pressure.

[rbuck351]

I got one of the first 223 rifles in my home town some 40 years ago It was a Rem 700V. the first 1500 or so rds through that rifle were 5.56. All were 1970s LC ball and worked fine. This was before they came out with the green tip 62gr stuff. After a emptied a bunch of the 5.56, I did load those with different Speer and Sierra soft point and HP bullets. It would print the 52gr Speer HPs right at 5/8 ". 6 or 7 thousand rds later it will still shoot a bit under 1". Still haven't shot a 62gr through it.

[Larry Gibson]

"Can't" is a big word there; you surely can or it wouldn't be a hazard because it wouldn't be possible. The right word is "shouldn't" because the 5.56 is something of a "Plus P" round and most .223 rifles aren't proofed for that level of pressure.

Ruger, Winchester, Remington, Savage, CZ, ARs, et al, actions are not "proofed" for any individual cartridge. They are all made to the same strength standard regardless of the cartridge's MAP. All of them are chambered with for cartridges that can develop 64,000+ psi in normal use. DO we really believe, for instance, that my Savage M12 which was originally chambered in .223 Remington [had several thousand M855s shot through it w/0 a single hic up] was only "proofed" for the .223 cartridge and would be unsafe in .308W? It is now a .308W btw and I'm shooting match loads loads generating 61,000 psi (measured, not guestimated). Am I to believe my M70 action in .223 Remington is somehow a less strong action than the same model chambered in .243W or the one chambered in .308W? Am I to believe my .223 Remington chambered M700 is less strong because the cartridge MAP is 56,000 psi than my M700 in 22-250 with that cartridges MAP being 65,000 psi?

NO, the actions are all made to withstand the highest psi of any cartridge the action is to be chambered in. To commercially make actions Talking modern rifle actions here) based on individual cartridge MAPs would be an expensive proposition and not profitable. It just isn't done.

[Larry Gibson]

I got one of the first 223 rifles in my home town some 40 years ago It was a Rem 700V. the first 1500 or so rds through that rifle were 5.56. All were 1970s LC ball and worked fine. This was before they came out with the green tip 62gr stuff. After a emptied a bunch of the 5.56, I did load those with different Speer and Sierra soft point and HP bullets. It would print the 52gr Speer HPs right at 5/8 ". 6 or 7 thousand rds later it will still shoot a bit under 1". Still haven't shot a 62gr through it.

Yours, like my own M700V purchased in '72, no doubt has a 12" twist. While it will shoot the 62 gr M855 w/o any problem accuracy will be poor if existent at all. Been there, done that......

[Drm50]

The first I saw of the 223/5.56 deal was the H&R Handy Rifles that had stamped in barrel not to fire 5.56 Military in them. Since military had went to heavier bullet and different twist it would cause increased pressure in older 223 chambers. I shot thousands of 55gr GI loads out of Ruger#3 and Rem 788. It was very noticeable if you were loading with IMR powder that military case had less volume than commercial 223. I did know exactly by filling cases with syringe. I don’t know of any catastrophes while I was in business. The major companies all had their milspec 5.56/ 223 and since it was the cheapest I sold a lot of it. Most was used in 223 bolt guns. I have never loaded anything heavier than 55gr in my 223s. In fact I load 55gr in 222 and 220swift too. Sacrifice a little velocity for accuracy.

[USMC87]

I really appreciate the great information guys!

[M-Tecs]

Good read here. https://www.luckygunner.com/labs/5-56-vs-223/

[M-Tecs]

"Can't" is a big word there; you surely can or it wouldn't be a hazard because it wouldn't be possible. The right word is "shouldn't" because the 5.56 is something of a "Plus P" round and most .223 rifles aren't proofed for that level of pressure.

US firearms are not proofed like some of the European Firearms are. In the US at best a small random percentage is proof tested. Ever see a proof mark on a US manufactured firearm unless it was shipped overseas? In some countries such as England and Italy every firearm is sent to a proof house and every firearm is proof fired and it carries the appropriate proof mark.

Larry is correct as usual. In the US most centerfire rifles are volume produced in medium or standard length with the same material and heat treat standards.