In a 223 chamber on a remington 700, who shoots 5.56 and has it caused you any problems? Looking at a 223 700 and have alot of 5.56 ammo that I want to shoot but dont know if its going cause any issues.

5.56 NATO rounds are loaded to higher pressure than 223. I wouldn't do it. But that's IMO only.

You will be fine.

Heavy bullets may jam im the lead of a 223 chamber. The 223 chamber is shorter throated and the 5.56 cartridge slightly higher pressured. The 223 loads normally stop with bullets of 55/60 gr, while the 5.56 will accept bullets to 90grs.

Hell,the bolt on my Kimber won't close on an 5.56,that's why I have an Armalite and do it right...

I believe the issue of 5.56 ammo in bolt-action .223s is all about jamming the bullet into the lands. There's an awful lot of conflicting "information" out there, and some of it comes from folks I would think I should be able to trust...nonetheless, I think they are wrong. Here are some links to info put out by folks who should know...

This came from wiki, IIRC. Not the most reliable source of politically controversial information, but usually is fairly reliable on technical questions:

5.56�45mm NATO

5.56�45mm NATO with measurement, left to right: bullet, empty case, complete round with bullet in case
Type Rifle
Place of origin United States
Service history
In service Since 1962
Used by NATO
Wars Since Vietnam War
Production history
Designer Remington Arms
Specifications
Parent case .223 Remington
Case type Rimless, bottleneck
Bullet diameter 5.70 mm (0.224 in)
Neck diameter 6.43 mm (0.253 in)
Shoulder diameter 9.00 mm (0.354 in)
Base diameter 9.58 mm (0.377 in)
Rim diameter 9.60 mm (0.378 in)
Rim thickness 1.14 mm (0.045 in)
Case length 44.70 mm (1.760 in)
Overall length 57.40 mm (2.260 in)
Case capacity 1.85 cm3 (28.5 gr H2O)
Rifling twist 178 mm or 229 mm (1 in 7 in or 9 in, originally 1 in 14 in)
Primer type Small rifle
Maximum pressure (EPVAT) 430.00 MPa (62,366 psi)
Maximum pressure (SCATP 5.56) 380.00 MPa (55,114 psi)

According to the info I've been able to dig up, SCATP standards are practically identical to SAAMI standards. EPVAT specifies a pressure measurement in a different physical location---near the neck, I believe.


Here is a page out of a 1994 publication of the Department of the Army. Chamber pressure for M193 ammo is given as 52,000 psi.



For now, I am in the camp that says 5.56 NATO ammo is NOT loaded any hotter than commercial .223 Remington can be. I've posted the evidence to support that position, but I won't claim it PROVES it. There may be more to the story.

The only primers I've ever blown have been from 5.56 NATO fired in a .223 chambered AR15. YMMV

While the external case dimensions are very similar, the .223 Remington and 5.56x45mm differ in both maximum pressure and chamber shape. The maximum and mean pressures for some varieties of the 5.56 mm (different cartridge designations have different standards) exceed the SAAMI maximum for the .223 Remington, and the methods for measuring pressures differ between NATO and SAAMI.[2] The 5.56 mm chamber specification has also changed since its adoption, as the current military loading (NATO SS-109 or US M855) uses longer, heavier bullets than the original loading. This has resulted in a lengthening of the throat in the 5.56 mm chamber. Thus, while .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, firing 5.56 mm ammunition in a .223 Remington chamber may produce pressures in excess of even the 5.56 mm specifications due to the shorter throat.[3]

Where did that come from, Swifty? I'd like to look it over if it's available on line.

I need to find the documents I've downloaded and see if I can find info on the other 5.56 loads. Based on the above, there may be a lot more variation within the 5.56 family of cartridges. Unless the specs for M193 have changed since 1994 I would stick with the opinion that it is loaded to the same pressure as SAAMI-spec .223 Remington, but maybe M855, SS-109 or other variants are loaded to different specifications.

http://www.ammunitionstore.com/content/5.56%C3%9745mm%20NATO.pdf

I just happened to run across this while looking for info on EPVAT. Page 6 is particularly interesting.

Page 7 of your document.
Using 5.56 mm NATO mil-spec cartridges (such as the M855) in a .223 Remington chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and SAAMI recommends against the practice.

Page 6

. The dimensions and leade of the .223 Remington minimum C.I.P. chamber also differ from the 5.56 mm NATO chamber specification.

Whether or not I stated it right, I would still not put mil-spec / 5.56 NATO rounds in my 223 bolt gun.

I used to shoot Whinchester ball ammo or what ever it was called back in the 80's in a BDL. I also shot a lot of BlackHills remanufactured fmj. That's was before for the net and all it's knowledge.

Those where the days 9.99 a box of 50, and 3.99 for 20.

http://www.ar15.com/content/page.html?id=434

A USN buddy brought back cases to 5.56 from Nam. He has been shooting it in his 1970s 700 223 forever ...... problems ZERO.

Good info. Going to inject a little different perspective. Look to the chamber also.

5.56�45 NATO Chamber OAL: 2.550

.223 SAAMI Chamber OAL: 2.410

Wylde Chamber OAL: 2.445

The tighter chamber on the SAAMI spec .223 along with the usually higher pressures 5.56�45 rounds are loaded to is what causes the danger in using 5.56 NATO in a gun chambers for .223 Remington. Pressures can spike up to 15,000psi.
The Wylde chamber almost splits the difference between the SAAMI .223 Remington and the 5.56�45 NATO. This means a lower pressure spike since its not as tight as the SAAMI chamber but a shorter jump to the rifling than the 5.56�45 chamber has. Thats the difference between a 5.56�45 NATO, .223 Remington, and .223 Wylde chambers. Its not overly complicated or this crazy weird stuff, just OAL differences that have an effect on safe pressures for a chamber.


Chamber specs are here also. http://www.againsttheberm.com/2012/11/223-sami-nato-and-wylde-chambers/

I think the differences in the chambers is really the major point of concern.

I saw an awful lot of information today which I had not seen before. One reason is that I used "EPVAT 5.56" as a search term instead of what I had done in the past.

Unfortunately there are a lot of resources out there which make assertions that are at variance with what I would consider the most authoritative sources, which would be documents from agencies within DoD.

One thing that has complicated comprehension of all the info out there is that there was a time when pressure measurements we now refer to as "c.u.p." were once commonly referred to as "p.s.i." I have not been able to ascertain just exactly when the US-made 5.56 ammo began to be evaluated by the SCATP standard. There are several DoD originated documents available on line referring to the pressures of M193 and M855 ammo as being 52,000 psi, but there are others that quote 55,000 psi. I believe that the former are copper-crusher numbers and the latter are piezo measurements.

Some information flatly states that the EPVAT standards include pressure measurement identical to the CIP method but also incorporate additional performance criteria. The same is said about the SCATP standards vis-a-vis the SAAMI pressure measurement methodology.

It's a tangled web, to say the least.

I have shot hundreds of 5.56 rounds through my Rem 700 and a lot of 5.56 cases that have been shot out of my 5.56 chambered Sig AR and then reloaded and shot out of the Rem 700 with no problems.

I do use lighter bullets in the 35-55g range and that might be a key in working it right.

The most accurate load out of the Varmint 700 is a 40g Nosler BT with LC brass and Rl-7 powder for outstanding velocity and accuracy.

The CASE dimensions are identical for the two rounds. The leade of the chamber in the rifles is NOT. It is safe to use reloaded (to .223 specs) 5.56 cases in a .223 chamber...but not all 5.56 spec ammo. Some might be ok...but some not.

I've never shot 5.56 ammo in my .223 for that reason. But 35 years ago, I opened up the headspace on a .308 by shooting surplus 7.62 ammo through it. Didn't know better at the time. No separated cases before...but after shooting 200 rounds of the 7.62 ammo, factory .308 cases separated on the first reloading (after firing), with a Lee Loader that only neck sized.

My first question is "How do you know it has a .223 chamber?"

There are a whole lotta rifles marked ".223" that actually have 5.56 Nato chambers. You may want to do some measuring. The freebore measurement is what you need to know.

I've run into British SS109 that isn't safe in 5.56 chambers. Let the temps get over 80F and it'll start blowing primers.

Thanks for the info, and I spoke to a couple other folks that said I should be fine as long as I stick to lighter weight bullets (under 70 grains and all my 556 ammo is 64 grain) that aren't jammed into lands. The more I think about it the more I imagine the factories are running a little more lead in the 223 chamber just so there aren't major problems. I'll let you know how it turns out. Thanks again

I've never had an issue mixing and matching COMMERCIAL ammo between 5.56 and .223 chambers. As TAK pointed out this does not always apply to military ammo. In addition my full boat 5.56 loads are to warm for a .223 chamber in an AR, but work fine in the .223 bolt rifles I've tried them in.

Of course, just because I do it, doesn't mean you will want to, but those are my personal experiences.

Free bore is the only difference

I have chrono'd both and checked charge weights from FC .223 55 fmj vs LC 55 fmj

Maximum length for the AR15 fed from a magazine is about 2.250

I did run across an informational PowerPoint presentation that suggested M855A1 ammo is loaded to a higher pressure. I am not sure I recall correctly but I think I saw 58000 psi. Not sure I could find that webpage again. Sucks getting old...CRS, ya know!

Shot a good amount of it in standard .223 chambers. I've never had an issue beyond the government accuracy.

I've fired several variations of 556 in an H&R Handi Rifle with no ill effects. I would expect the same result from a 700 Remington.