556 in Sako 85 223 Varmint. I say no, dealer says yes.

gregp74 said:

(I honestly don't care if it can shoot it anyway, just will help me decide if I sell this case of xm855 if I decide to sell my AR15.)

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Eh,,, Gotta ask,,,, Regardless of ".223 vs. 5.56" (With all the variables and confusion that subject evokes),,,, Why are you contemplating using LAP ammo in a bolt gun?

Unclear of you objectives, but I personally don't view your typical XM855 as anything ~special~ in the accuracy dept,, and 'while it will work' on certain critters for hunting, there are far, far better choices,,,

The SAKO you mentioned, by all accounts, appears to be geared more towards Hunting / Accuracy than range blasting,,, I personally believe that 'rolling your own' ammo to feed the SAKO would allow you to get the most out of it,,, (or the AR, for that matter,,,)

If you don't reload already, but may consider doing so somewhere down the road,,, those 1,000 pieces of brass current sitting under the XM855's (once shot) wouldn't be too bad to get you started with,,,, (I'm certainly not indicating you should pull them apart now just for the brass, but rather burn them up in the AR first and save the brass)

I don't know your exact situation, or if funds for the Sako would come from sale of the AR and/or the XM855. If so, well there ya go!

If funds for the Sako aren't coming from either the sale of the AR and/or XM455, consider selling the AR only after you burn up that XM855 in it. (Unless you know for sure you never will burn it up in the AR, then simply sell it...)

I haven’t seen anyone say this:

My understanding is that the difference is only significant in the semi auto gun because of the potential cycling issues. Any modern bolt action is going to be more than strong enough to handle the extra pressure.

The 1:7 is for the tracer rounds and unnecessary for bolt actions. The 1:9 seems to be the best unless you want to shoot slightly heavier bullets.

I too am looking for a bolt action in 1:9 and I’d like to shoot the M193 because it is cheap and consistent and I can set a poa and leave it to hit whatever I am looking at. If I want to step up in bullet weight or power I’ll go to the .243 I don’t own yet...

YMMV
Greg

gregp74 said:

it said something about ammo made ti CIP (?) European or SAAMI US standards.

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Pressure
C.I.P. defines the maximum service and proof test pressures of the .223 Remington cartridge equal to the 5.56mm NATO, at 430 MPa (62,366 psi). This differs from the SAAMI maximum pressure specification for .223 Remington of 380 MPa (55,114 psi), due to CIP test protocols measuring pressure using a drilled case, rather than an intact case with a conformal piston, along with other differences.[63] NATO uses NATO EPVAT pressure test protocols for their small arms ammunition specifications.

Because of these differences in methodology, the CIP pressure of 430 MPa (62,366 psi) is the same as a SAAMI pressure of 380 MPa (55,114 psi), which is reflected in US Military specifications for 5.56mm NATO, which call for a mean maximum pressure of 55,000 PSI (when measured using a protocol similar to SAAMI).[64]

These pressures are generated and measured using a chamber cut to 5.56 NATO specifications, including the longer leade. Firing 5.56mm NATO from a chamber with a shorter .223 Remington leade can generate pressures in excess of SAAMI maximums.

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https://en.m.wikipedia.org/wiki/5.56×45mm_NATO

http://www.accuratepowder.com/load-data/

What helps make it all more confusing is this reloading data. The 223 vs 5.56 velocity and pressures are different. Using the same components. The barrel twist rate is the only difference i see.

Other data from different sources, list loads that are different between action types and/or cartridges.

CoalTrain49 said:

Then why do some rifle manufacturers tell you not to do it?

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Lawyers and misinformation.

The reality is that all makers of .223 bolt guns know good and well that huge quantities of 5.56 surplus go through them. Every time this comes up, there's a simple challenge: provide evidence of even one time this was a problem. Of any sort. No one can, because it isn't a problem, because they're the same round.

If you look at the reamer specs you posted, you'll see there's no consistency at all. Some of the 223s have long freebore, some are short. Some of the 5.56s are long, some are short. Same goes for neck length and tightness at the shoulder - the .223 Wyld that is supposed to shoot 5.56 is most sensitive to not bumping backt he shoulder. There is no pattern, because there is no difference. They are the same round.

Here's more food for thought: the AR, where we run 5.56 all the time, is a very weak platform. The bolt lugs are too small and shear. That's why we're always MP testing bolts and they still break reliably with heavy use and it's worse with the newer higher pressure 5.56 military ammo, or at least so the Army says. And that's the pattern we're happy to shoot 5.56 in. But put it in a bolt gun that will handle 65KPSI WSMs on a magnum bolt face, but instead you're running 62KPSI or so (SAAMI style measurement) on a tiny bolt face with tons of extra steel because the cartridge is so small and watch out - you might hurt yourself because the barrel's stamped .223

Llama Bob said:

The reality is that all makers of .223 bolt guns know good and well that huge quantities of 5.56 surplus go through them. Every time this comes up, there's a simple challenge: provide evidence of even one time this was a problem. Of any sort. No one can, because it isn't a problem, because they're the same round.

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You obviously didn't read my reference to the Hornady manual and bullets suitable for .223 and 5.56 NATO. I'm not sure if you reload or not but if you did you wouldn't want to be loading 80 grain bullets for you .223 without knowing your chamber dimensions. Or maybe you would, I don't know, but I surly wouldn't do it. Hornady knows that some mfg's still chamber for .223. My Howa HBAR is not chambered for 5.56. Why, because they said it wasn't. They built the rifle, they should know.

You assertion that all rifles are now chambered for 5.56 isn't accurate. In your world of AR's nobody cares because they are all 5.56. Bolt guns, not so much. My suggestion, as others here have said, is, check your chamber first.

Here is one of the examples I found online of issues that can occur when firing 556 in 223 rifles..

I had some W-W white box ammo from work, 55 gr FMJ with a [5.56] NATO headstamp on hand..... . The Mini Mauser has a .223 stamped chamber. I never gave it any thought.

Accuracy was abysmal, 3-4 inches, from a rifle that will shoot 1MOA or less with ammo it likes. When I reviewed the string on the chrono I was shocked. The stuff was averaging over 3650 fps. ( I didn't write it down) Thats about 400 fps per second faster than commercial listings, from a 20" bbl. no less.

I have no idea what the pressure was, but feel it had to be significantly elevated to gain that much velocity. Won't be doing that again.
bamaranger

Whatever the pressure was I'm sure it's not what I'd consider safe.... If he hadn't been running his chrono he wouldn't have ever known... How many others have experienced the same thing and never even knew it?

I always say better safe than sorry. We preach gun safety. One thing that was taught to me is only use ammo that is made for the rifle (says 223, use 223). I'm not saying it won't work, I'm just thinking that we preach safety so shouldn't we keep safety as paramount to everything else?

gregp74 said:

Well the Sako arrived today. Briefly glancing at the manual said the usual only use what's stamped on the barrel but it said something about ammo made ti CIP (?) European or SAAMI US standards.

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You should be good to go for 5.56 then. I also notice that SAKO utilizes a 1:8” twist rate in their excellent cold hammer forged barrel. So you’re in business to shoot everything up to 77gr match ammo. I’ll bet you’re going to enjoy it.

See, SAKO more or less builds their gun how I’d like all of them to be made as a standard.

My understanding was the CIP does not distinguish the two, and considers them the same caliber, in which case any European proofed .223 would be under that system. The CIP pressure limit for .223 is about what the SAAMI number is for 5.56, still wouldn't hurt to call.

Bushpilot said:

No thanks.. I'll keep my .223 chamber... I don't want a lot of freebore or a 1/7 twist



How do you figure that?


Ha ha keep waiting...

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Well they did give a guy a Nobel for saying nuclear weapons were bad, and not much else.

Bushpilot said:

Here is one of the examples I found online of issues that can occur when firing 556 in 223 rifles..

I had some W-W white box ammo from work, 55 gr FMJ with a [5.56] NATO headstamp on hand..... . The Mini Mauser has a .223 stamped chamber. I never gave it any thought.

Accuracy was abysmal, 3-4 inches, from a rifle that will shoot 1MOA or less with ammo it likes. When I reviewed the string on the chrono I was shocked. The stuff was averaging over 3650 fps. ( I didn't write it down) Thats about 400 fps per second faster than commercial listings, from a 20" bbl. no less.

I have no idea what the pressure was, but feel it had to be significantly elevated to gain that much velocity. Won't be doing that again.
bamaranger

Whatever the pressure was I'm sure it's not what I'd consider safe.... If he hadn't been running his chrono he wouldn't have ever known... How many others have experienced the same thing and never even knew it?

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There's something very strange about this story. First, yes, velocity and pressure are closely related. 400 ft/s extra on .223/5.56 equates to maybe 30% over-pressure. That's BAD.

However, "mini-mauser" to me means Zastava, BRNO, or CZ. All three are CIP guns, and CIP doesn't even have a separate 5.56 vs. .223 spec. There's just one spec, like there's supposed to be, and it covers both - they're just different names for the same cartridge. So it's very hard to believe that the over-pressure was caused by putting in-spec ammo in a factory chamber designed for it. I suspect other causes such as a non-spec custom chamber, or possibly even internet fabrication.

Llama Bob said:

There's something very strange about this story. First, yes, velocity and pressure are closely related. 400 ft/s extra on .223/5.56 equates to maybe 30% over-pressure. That's BAD.

However, "mini-mauser" to me means Zastava, BRNO, or CZ. All three are CIP guns, and CIP doesn't even have a separate 5.56 vs. .223 spec. There's just one spec, like there's supposed to be, and it covers both - they're just different names for the same cartridge. So it's very hard to believe that the over-pressure was caused by putting in-spec ammo in a factory chamber designed for it. I suspect other causes such as a non-spec custom chamber, or possibly even internet fabrication.

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I tend to agree.

Bushpilot said:

Here is one of the examples I found online of issues that can occur when firing 556 in 223 rifles..

I had some W-W white box ammo from work, 55 gr FMJ with a [5.56] NATO headstamp on hand..... . The Mini Mauser has a .223 stamped chamber. I never gave it any thought.

Accuracy was abysmal, 3-4 inches, from a rifle that will shoot 1MOA or less with ammo it likes. When I reviewed the string on the chrono I was shocked. The stuff was averaging over 3650 fps. ( I didn't write it down) Thats about 400 fps per second faster than commercial listings, from a 20" bbl. no less.

I have no idea what the pressure was, but feel it had to be significantly elevated to gain that much velocity. Won't be doing that again.
bamaranger

Whatever the pressure was I'm sure it's not what I'd consider safe.... If he hadn't been running his chrono he wouldn't have ever known... How many others have experienced the same thing and never even knew it?

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That WW was probably commercial sale M193 stuff that gets made to the old specs, but sold on overrun. That stuff is always very fast to make velocity requirements even after sitting in storage for years. 3650 is very high, but 3500 is not all that uncommon, and I have heard of 3600 on occasion, all within the NATO pressure standard, just powder optimized for the case, and loaded by someone with a peizo transducer. Most people don't have chronographs, and never noticed. EDIT spec calls for 3165FPS -/+40 at 78 feet. Most people set up a chrono 10 feet or less. Some of the old military stuff goes way beyond that.

So it's very hard to believe that the over-pressure was caused by putting in-spec ammo in a factory chamber designed for it. I suspect other causes such as a non-spec custom chamber, or possibly even internet fabrication.

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As far as the "internet fabrication" is concerned, here is where I found it at the bottom of the page, so "if" there is any "fabrication," it's not on my part.
https://thefiringline.com/forums/showthread.php?t=560162
However, I have no reason to believe this story is untrue, especially when the SAAMI says shooting 5.56 in a 223 is an unsafe practice. I used to be more in the "223 or 5.56 it's all the same" camp but the more I study the subject the more I am convinced that there are some exceptions. I believe the difference in the amount of freebore between the two is at the crux of this issue.

Bushpilot said:

As far as the "internet fabrication" is concerned, here is where I found it at the bottom of the page, so "if" there is any "fabrication," it's not on my part.
https://thefiringline.com/forums/showthread.php?t=560162
However, I have no reason to believe this story is untrue, especially when the SAAMI says shooting 5.56 in a 223 is an unsafe practice. I used to be more in the "223 or 5.56 it's all the same" camp but the more I study the subject the more I am convinced that there are some exceptions. I believe the difference in the amount of freebore between the two is at the crux of this issue.

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I didn't mean to imply that you were making something up, but that doesn't mean the story is straight.

Assuming a CIP-spec gun, the gun DID have a generous freebore. Also, there's a limit to what even being jammed into the lands will do to pressure and velocity. It tends to increase pressure without increasing velocity - I said above there is a relationship, but jamming the lands is sort of an exception to the rule. In .223/556 jamming the lands will increase pressure by about 10KPSI, but only increase velocity by about 50 ft/s. You can't explain a 400 ft/s increase that way.

I understand being cautious about safety, but this story doesn't make a lot of engineering sense.