Question about loading .223 Rem "hot."

[SL1]

I am still contemplating purchase of my first .223-chambered rifle, and am researching its potential flexibility in a bolt-action. I have figured-out how to load it down to approximate .22 rimfire power, and will probably shoot it mostly around the power level of the .222. But, I am still working on how "hot" it can be loaded in a bolt action.

One thing that confuses me is that the older SAAMI pressure standards in CUP seemed to put the .223 in the same max pressure category as the .270 Winchester and the .30-'06 Springfield, (52,000 CUP compared to 54,000 and 50,000). But under the newer SAAMI standards in PSI, the .223 is only rated for 55,000 psi, compared to 65,000 for the .270 and 60,000 for the .30-'06. In fact, it seems that ALL of the cartridges with the .223 head size are maxed at about 55,000 psi in the SAAMI standards. And, I recently read (in another thead here) a comment about .223s having case-head expansion as a fact of life.

So, I am wondering just how much pressure a .223 Remington case will take before it gets to the point that the primer pocket is too loose to use after two or three reloadings. And, how much difference is there between brands of brass in this regard?

SL1

 

[mehavey]

My experience has been that for .223 purposes, the AR action is as strong (or stronger) that its bolt action family. "Hotness" sensitivity is therefore a function of the cartridge itself. Pressurewise its components begin getting (gracefully) stressed in the mid 55K region.

The Lapua/LC family of brass seems to last longest, primer pockets being the weak link (and easy to monitor failsafe mechanism). Winchester cases seem to go earlier -- but then Winchester is cheap/Lapua expensive. Yes, the hotter loads are hard on the case head. (Bottom Line: there ain't no free lunch.)

That said, the .223 Rem is one of the best "do-all" cartridges for its class. In its various twist combos it does everything pretty well and is available all over the place ("ubiquitous" for the upper-crust cognoscenti) in being able to pick up ammunition anywhere in the world, a broad spectrum of components, and work with lotsa different powders & bullets. Even in its moderate loads it will kill white tail efficiently, reach out quite a ways and touch coyotes, ...and utterly destroy crows/ground squirrels/prairie dogs.

It kills people real well too.

But if/when I need a screamer in the EargenSplittenLoudenBoomer class to utter vaporize something... I bring out the Swift.

Right tool for the right job, doncha know.

 

[Mobuck]

Since I load .223 for several rifles, I stay on the conservative side of the "hotness" level. My theory is that the /223 is a medium/small case with medium performance. If I want/need more, I go to the 22/250,220 Swift, or 243 Win.

 

[5R milspec]

the best way to go about this is to just go on and get the rifel of choice.then load up useing powders/bullets of choice with a ladder test.and when you start getting pressure signs you are not happy with then work around the safer loads.

for me 27.5gn of varget is a compreesed load in my rifel.even from the load web site its a compressed load useing a 55gn bullet.but with that said I still have a pretty good looking primer.but will not go over that amount of powder for the load.stay safe and always load in a safe frame of mind.its not all about how fast you can reach the target.I would rather lobb the bullet to the target with great accuracy than burn out my barrel.yes I know the one load I just stated is a fast load but the only load at this time the rifel likes.but wish it wasn't that way.still rather save the life of my rifel.just hope the info helps and if you need to take it with a grain of salt.want hurt my feeling at all.

 

[mehavey]

....yes I know the one load I just stated is a fast load but the only load at this time the rifel likes....

What cases are you using?

 

[dlb435]

Best not to push it in a bolt action gun. Is the barrel marked 223 REM or NATO 5.56? The two rounds are identical except for the pressures they develop. A barrel marked 5.56 NATO will be good for 60,000 CUP while barrels marked 223 REM are only good to 50,000 CUP. That's 20% more power in the NATO round. That said, I have never found published data for 5.56 NATO reloading. Just lots of speculation.

 

[Jim243]

DLB435

If you find a BOLT ACTION RIFLE marked 5.56 please let me know.

Jim

 

[SL1]

dlb435,

I seriously doubt that the BARRELS marked "5.56 NATO" can handle more pressure than the ones marked ".223 Remington" because they are going to be the same action with barrels made out of the same steel and chambers cut to the same diameter (or maybe even a little more diameter for the NATO round). The only important difference in the chambers is in the throats, where there is a little more room for the case neck length and bullet ogive in the NATO chamber. And, THAT is supposed to keep the NATO rounds from giving MORE than their rated pressure.

The thing that WOULD interest me is whether the NATO CASES handle pressure better than the .223 cases. But, from what I have heard, there is actually little difference in the cases.

5R Milspec,

Of course I realize that I can find-out for myself how hot the rifle that I buy can go without shortening brass life more than I want. But, I am still trying to figure-out exactly what features I want in that rifle. If I decide to push it to handle the small deer around here, I will want it to handle longer, heavier bullets than if I decide to limit my .223 to predators and go to my .270 for deer. If I decide to shoot targets at long ranges, again I will want heavy bullets at higher velocities. Those heavier bullets require tighter twist rates, and higher velocities require longer barrels if the pressure isn't going very high.

I have read that people shooting the NATO round at 600-yard targets use some pretty hot loads. But, I don't know their particular definitions of "hot", or, for that matter, how many times they can reload their cases.

SL1

 

[Sevens]

Best not to push it in a bolt action gun.

I can only think of one platform that is better for "pushing it" and that would be a pressure test barrel.

If you can't "push it" in a bolt gun, then lever, pump, single shot and semi-auto's need not apply.

 

[Brian Pfleuger]

I can only think of one platform that is better for "pushing it" and that would be a pressure test barrel.

If you can't "push it" in a bolt gun, then lever, pump, single shot and semi-auto's need not apply.

That's what I was thinking too.
Isn't a bolt gun the strongest thing available?

 

[SL1]

[Hmmm, my last reply seems to have evaporated into "cyberspace."]

Here is the short version: I am not asking how "safe" it is to exceed the SAAMI max pressure limit in the .223/5.56 NATO case in a bolt action rifle. I can keep myself safe while working-up loads for the rifle AFTER I BUY IT.

What I AM asking is whether pressures above 55,000 psi (the SAAMI limit), when fired in a BOLT ACTION rifle that is desgned for 65,000 psi, will cause the brass to have excessive primer pocket expansion BEFORE reaching the design pressure for the action.

For cases with heads the diameter of the .30-'06, you CAN go to 65,000 psi, even when using cases for cartridges like the 7mm Mauser, which were designed with lower pressure standards. BUT, I do not have much evidence for thinking that the same is true of the cases with heads of the .223 Remington diameter.

So, I am asking for EXPERIENCE of members on this forum when they take pressures in .223/5.56 case above 55,000 psi.

SL1

 

[wncchester]

"So, I am wondering just how much pressure a .223 Remington case will take before it gets to the point that the primer pocket is too loose to use after two or three reloadings."

I wonder too. But, I nor anyone I know has pressure measuring equipment so I haven't a clue how to find out how much it would take to expand primer pockets after reloading two-three times without testing for it with several brands of cases (they do vary) in my own rifle. And even then I wouldn't know what the pressure was. ??

 

[William T. Watts]

Whatever expansion that occurs with factory loaded ammunition (measured around the expansion ring measured with a mic that can measure to .0001") that part of the case that isn't supported by the chamber should be considered the limit. Whenever your handloaded ammo using new cases (I.E I use R-P) equals the same expansion it's time to stop there, if the expansion of your loaded ammo exceeds that by .0001 you've crossed the line. If you need more velocity than that you don't need a .223 you should consider another caliber. FWIW a chronograph would be very helpful if you are going to try to load on the outer edge of the envelope. If primer pockets open after a couple of firings (primers are flatten or cratered) plus the added thrust being applied to your bolt face it ain't worth it! IMO William

 

[Unclenick]

The whole issue is really much ado about nothing. If you look at the SAAMI and the CIP specifications for the same cartridge, they are:

SAAMI
52,000 cup
55,000 psi

CIP
53,664 cup
62,366 psi

As far as I know, when we developed the .223 and adopted it as the 5.56×45, we sent NATO the same reference loads we use, and that is what they measured the pressures to be. What you are seeing is the difference in port locations for the pressure transducers and other small differences affecting the already very scattered relationship between cup and psi. Yes, there is a correlation, but its precision may only be counted on to be in the vicinity of 10-12,000 psi if you don't confine testing it to a single test gun and cartridge over a wide range. These kinds of pressure measurements are approximations.

If you look at other cartridges that were once rated by SAAMI at 52,000 cup and average the new SAAMI psi ratings, you get about 61,700 psi average conversion, IIRC? I did that calculation once. The CIP test result is clearly much closer to that average, and I have no hesitation working with that CIP number rather than the SAAMI number. I do, however, keep in mind Geoffry Kolbe's admonition that throat wear increases rapidly as pressures get up above what works out to be not quite 60,000 psi, so I tend to limit myself to that unless I don't intend to put a great many rounds through the gun in its lifetime.

Consider that .223 is chambered in many bolt guns also available in .308. The .308 has more surface area and in the same gun model is surrounded by thinner metal. The bolt thrust is proportional to head area, so, at the same pressure, the .223 produces less bolt thrust. All in all, unless you have a brass failure, .223 should be possible to run at higher pressures than .308, if you don't care about throat wear. You do need to keep an eye on the brass.

NATO chambers are about .004" longer and .002" wider than .223 chambers, and they have a 0.025" longer freebore. These are to make full auto feed more reliable and to accommodate special bullets that need more freebore to avoid jamming into the throat. Since peak pressure is partly dependent on the volume the case expands to in the chamber, the difference amounts to around a third to half a grain of increased expanded case water capacity in the NATO chambers firing the same round as you fire in a SAAMI chamber. That volume amounts to 1,000 psi to 2,000 psi difference in pressure with a given full powder load. Not enough to get excited about. The longer freebore will allow a bit more gas blowby before the bullet obturates the bore, but the difference will be in that same range. I suppose you might get a total of 10% less pressure in the NATO chamber in an extreme case, but most of the time the difference is probably going to be under half of that, so I don't worry about it because that falls within normal load shot-to-shot variation.

 

[mehavey]

Very useful chart. Very.

The .223 specs show a 25% faster throat taper. This would engage the bullet at a shorter freebore distance relative to that of the 5.56 chamber,... if there is any freebore left at all (using a NATO round in the .223 chamber) and you're not jammed into the rifling that point.

 

[SL1]

A lot of fairies seem to be dancing on this pinhead, BUT

none of them seem to be addressing MY question.

OK, I DO know that few of us have pressure-testing equipment. But, it is reasonable to assume that we are getting something like SAAMI max peak pressures when we load to the max charges in our manuals. And, if we are carefully using our chronographs and our QuickLOAD programs, we SHOULD have reasonably educated estimates of what our pressures are running.

And, I know that some of us have "pushed the envelope" on several cartridges. I would not be surprised if Clark has destroyed some rifles that shoot .223/5.56 ammo (on purpose, since that is what he does). So, I would expect that SOME of the members of this forum have exceeded the SAAMI standard in bolt actions chambered for the .223. And, I would expect that SOME of the members have been careful to estimate the pressures when they did it.

SO, PLEASE let's not have any more answers that tell me to get a rifle chambered for another cartridge or that nobody actually knows what pressure they really have.

Let's just restrict the answers to what I am asking about: when you exceed the charge weights that pressure-tested data indicate will produce appoximately 55,000 psi in a test gun, how does the brass hold-up in commercially available bolt action rifle at pressures you would reasonably estimate to be 60,000 psi? Same question for 65,000 psi?

Thank you (I hope).

SL1

 

[mkl]

So, I am wondering just how much pressure a .223 Remington case will take before it gets to the point that the primer pocket is too loose to use after two or three reloadings. And, how much difference is there between brands of brass in this regard?

Okay, I'll go out on a limb here, and tell you that the pocket will start to expand at around 75,000 psi as long as we are talking about new one or two times reloaded brass.

I will also tell you that a Remington 700 BDL will handle that pressure and not blow up. I would suspect that that pressure is about the "blue pill" pressure that the gun is proofed with.

I have shot at least 12 different military 5.56 cartridges in my Remington 700 with no problem. These rounds cycle through my AR-15 just fine also. I have never noticed a difference in pressure signs from rounds shot in the 700 or in the AR-15.

On a couple of occasions I have unintentionally exceeded the SAAMI pressures in the Remington 700, up to what I am guessing is around the 75k psi I mention above. Primer pocket did open up a small amount while the rim diameter expanded .003" at which point I stopped shooting that particular load.

So perhaps the short answer is that the quality bolt guns are at least as strong as the AR-x series, and if I had to bet, are just a tad stronger.

Brass that I inadvertently exceeded pressure on was Federal and Lake City as best I recall. No blow ups; just primer pocket and case rim expansion.

 

[SL1]

MKL,

Thanks for being responsive. I don't have any intention of loading to 75,000 psi. I am interpretting what you wrote to mean that you don't think that brass would have any significant problems at 60,000 to 65,000 psi. That is what I had initially expected, but was led to question by some comments in other threads on this forum.

Being able to load to 60-65,000 psi would allow some "room" for a 22" barreled .223 to reach the 1200 ft-lbs that my state requires for deer rifles with bullets that seem appropriate for deer in such a light caliber. The manuals say that it CAN be done within the SAAMI spec, but with only an extra 50 fps or so and with just one of the listed powders. In my experience, that isn't really a guarantee that MY rifle is going to get to that velocity with that charge.

Based on QuickLOAD calculations, it seems that I could add another 2" to the barrel length to gain another 60 fps or so of margin. But, with a heavy barreled gun, that is a significant weight addition. Going to 60,000 psi adds a little more margin than that, and 65,000 psi more than doubles the margin gained from 2" of barrel. Since I would not be shooting a deer load very often, if at all, I am not too worried about barrel life at 60,000 psi. My .270 Winchester seems to do fine in that department, and it is using a lot more powder to get to 60-65,000 psi.

As I said in the inital post, I will probably be shooting this rifle mostly at about 50,000 psi or even less, emulating a .222 or even a rimfire .22. What I am trying to figure-out now is how much flexibility to try for in the parameters for my new gun. Should I stop at coyotes, or stretch for small deer? My choice will depend on how much weight and balance it would cost me.

SL1

 

[mehavey]

If that's all it is (1,200 ft-lbs), that's easy.

77gr Sierra MK over 23.3gr TAC: 2650 fps @ 48,500psi = 1200 ft-lbs
65gr Sierra SPBT over 25.3gr TAC: 2890 fps @ 49,600psi = 1200 ft-lbs
55gr Sierra SPBT over 26.4gr A2495: 3140 fps @ 48,700psi = 1200 ft-lbs
52gr Sierra SP SemiSP over 28.7 W748: 3280 fps @ 51,000psi = 1200 ft-lbs

Now this is out of my 20-inch AR15 without even breathing hard.





The usual disclaimer: Check all these loads for safety in your rifle using your reloading manuals.

 

[mkl]

Should I stop at coyotes, or stretch for small deer? My choice will depend on how much weight and balance it would cost me.

Well, if I can recommend a small deer rifle, I would suggest a .243 Winchester shooting the 100 grain Nosler partition bullet behind a case full of IMR 4350. Have taken over 15 deer in the 150-225 pound range with that load and never had them move more than 50 feet from where I hit them (front shoulder; loose a little meat, but never the deer).

That said, I was turkey hunting several years ago with my ar-15 and the 55-grain FMJ bullets (a service load, not a hand load) and just about dusk a very large whitetail doe walked out about 125 yards away.

It was deer season and does were legal in my Texas county. Matter of fact, limit that year was three does, but only two bucks. [Brown county, Texas. Check it out if you don't believe me.]

Anyway, the big doe was facing me and I decided to go ahead and take her for my chili meet. The 55 grain FMJ military bullet hit her right at the base of the neck as she was facing me straight on. Went in and started to tumble and ended up taking out about a foot of her spine.

Instant kill. The animal never suffered nor knew what hit her.

Guess the point of this post is that bullet placement is much more important than bullet type as far as the .223 is concerned. The .223 is not a very good deer gun when compared to the old reliable 30-30 or the .,243 Win. etc., but it will do the job with exact bullet placement.

Placement, not bullet type nor speed, is the key to a sure kill with the .223; neck, head, and spine shots are your best bet.

Just my opinion, but I have "been there and done that."