5.56 in Remington 700

[Tommy T]

A friend gave me 5 boxes of mil spec 55 grain 5.56 ammo. My only 223 is a Remington 700. I did a Google search and found a lot of conflicting info. Many posters said no problem using this ammo, as the size difference is minuscule, and strong bolt actions have enough "chamber play" to safely fire it. Others said it's dangerous and could be a threat to life and limb. I'd be interested in knowing what folks with more knowledge than I on this topic think. Thanks

[WCMG]

A gunsmith once told me, "If your firearm can't handle 5.56, then I wouldn't shoot 223 out of it", meaning if there's a possibility of failing by shooting 5.56, then is that firearm something you really should be shooting.

Yes, 5.56 has an increase chamber pressure and if your rifle is chambered in 2.23 then the smart people who designed that firearm specifically put 223 on the barrel for a reason.

But in the real world, I personally take my gunsmith's advice. Here's an short article about this very subject that I often pass onto people who ask me this question:

https://exclusive.multibriefs.com/co...mington-rounds

[abner13]

if your rifle is chambered in 2.23 then the smart people who designed that firearm specifically put 223 on the barrel for a reason.

Ruger Mini-14 rifle barrels have always been marked .223 Remington , yet in the owner's manual pg.2 , they clearly state any commercial .223 or military-spec 5.56 NATO is perfectly fine.

Gotta have a good understanding of the differences in chamber specs , the differences in the ogive of bullets , most importantly , the amount of leade from chamber neck to full rifling. Similar in effect to what is known as "freebore".

See also .223 Wylde. Basically a hybrid chamber using the .223 Rem chamber and the longer leade of the 5.56 NATO.

The 700 is a strong action , and there's a lot of steel around that little case.

[SgtRecon]

Shoot it with no worries, I have been doing this for decades with zero signs of over pressure, accuracy, feed or function issues, same goes for 7.62x51 /.308. It has been blown out of proportions by bloviating so called internet gun experts

why are we using 223 dies and load data for our 556 rifles ?

much like the ford vs chevy...45 vs 9mm....Glock vs 1911 endless discussions

[chauncey]

If you have a problem, it will be the 5.56 being difficult to feed into the chamber and extract.

My understanding is that this is due to military brass being a little thicker and the brass being minimally larger in size.

I have Ruger Predators in both 223 and 308. They both feed and extract 5.56 and 7.62x51 military brass with no issues.

My Remington 783 (maybe its a 788?) in 308 doesn't like military brass to the extent I won't use 7.62x51 in it any more. Its just not worth the hassle.

It depends on how the manufacturer sizes the chamber.

YMMV

[Hokkmike]

CZ says I can use both in my .223 527. Otherwise, I would not.

I have read too many conflicting opinions on both sides and would choose to err on the side of protecting myself. Besides, (except for the current ammo panic) .223 is plentiful.

[Delkal]

why are we using 223 dies and load data for our 556 rifles ?

The case dimensions between the two are identical.

The difference between the two is in the amount of freebore in front of the case mouth before the bullet hits the rifling. Military 5.56 barrels have a longer spec freebore to give the bullet more "jump" before it hits the rifling. This lowers pressure and a minimum SAAMI 223 spec chamber with a short leade could increase pressure. But I think the rifle companies know this and Remington and others have been putting sewer bore extended leads on their rifles for years to keep pressures down. I would not be surprised if some of the leads are longer than Nato specs. Famous last words but I don't think you will blow up with a production chamber. I would NOT shoot 5.56 in a custom match chamber with the minimum specs though.

[JenniferG]

If you're concerned about the chamber length of the Rem 700 you can find the dimensions online or have a competent gunsmith find the chamber length for you with their gauges. I would check first because as it's been pointed out that if the bullet while chambered touches the lands of the rifling then over pressurization can occur. The bullet has to have a bit of space called leade before the bullet contacts the rifling lands when it's fired.

[Yoder]

Apparently the pressure difference is a myth. Two different types of testing were used when originally defining the limits:

"and more accurate/reliable results. And it*s when you compare the SCATP-5.56 pressure rating to the SAMMI 223 Remington pressure rating that things become clear:

5.56 Maximum pressure (SCATP 5.56) 55,114 psi
223 Maximum pressure (SAAMI) 55,000 psi
The conclusion: 223 Remington and 5.56 NATO have essentially the same maximum working pressure rating. "

This was a pretty good article:

https://ultimatereloader.com/2018/08...cts-and-myths/

[Gunplummer]

What JenniferG said. And no, the case measurements are not the same. Not on the 5.56, the .308, the 30-06, or the 30-40 Krag. The brass IS thicker. Anybody that has been reloading military brass for years knows about neck turning. "Choking" the neck of a cartridge has the same affect as ramming the bullet into the rifleing before firing. Will it blow your head off? Probably not, but you can have extraction and feeding problems because of it. I was around before the internet and SAAMI had nothing to do with milspec ammunition. The chamber and cartridge drawings for Milspec ammo are originally from Frankford Arsenal.