556 ammo question
- Thread starter alanwk
- Start date
Yup just use .223 data. The only difference is 5.56 allows for ~ 5% more chamber pressure and has a longer throat. I would wager almost all semi auto .223 rifles today actually has a chamber reamed to safely accept 5.56... just for operator safety.
At any rate, the rounds are essentially interchangeable so the data is essentially interchangeable. That extra 3k chamber pressure allowance really gets you next to nothing
At any rate, the rounds are essentially interchangeable so the data is essentially interchangeable. That extra 3k chamber pressure allowance really gets you next to nothing
Marco Califo
New member
The first problem is finding 5.56mm dies 
As i understand it 5.56 and 223 cartridge dimensions are identical. However 5.56 is military cartridge and does not have saami specs so to speak, thus almostno load data. Western and hornady both have 5.56 load data. From what i have seen it goes just a touch higher than 223 data, but not by much. Personally i have started seeing pressures signs with standard 223 data and would not want to push into 5.56 ranges anyway.
For example, max charge, 62g bullet from Hornady 11th.
Cfe223
223, 27.4g
5.56, 27.7g
Tac
223, 24.7g
5.56, 24.7g
Win 748
223, 25.5g
5.56, 25.7g
Might interest you since hornady has 5.56 data. hornady has a digital manual. You can get the app. You have 2 options. option 1 is to to buy the full manual for $20 if i remember right. Option 2 is you can purchase individual cartridges for 99 cents each and just buy what you need.
On another fun note that may be helpful to you. I did some testing with my 16in ar the other day with factory ammo and my general purpose training load.
10 shots each, chrono set up 15ft from the muzzle.
Winchester M193, (5.56), avg 3056fps, es 110fps, sd 30fps
PMC x-tac M193, (5.56), avg 2997fps, es 111fps, sd 35fps
Hand loads (.223), avg 2946fps, es 48fps, sd 15fps
My general purpose training load.
LC brass
CCI #41 primers
55g Hornady FMJ, Col 2.200
CFE223 27.0g (thrown with a hornady powder thrower)
For example, max charge, 62g bullet from Hornady 11th.
Cfe223
223, 27.4g
5.56, 27.7g
Tac
223, 24.7g
5.56, 24.7g
Win 748
223, 25.5g
5.56, 25.7g
Might interest you since hornady has 5.56 data. hornady has a digital manual. You can get the app. You have 2 options. option 1 is to to buy the full manual for $20 if i remember right. Option 2 is you can purchase individual cartridges for 99 cents each and just buy what you need.
On another fun note that may be helpful to you. I did some testing with my 16in ar the other day with factory ammo and my general purpose training load.
10 shots each, chrono set up 15ft from the muzzle.
Winchester M193, (5.56), avg 3056fps, es 110fps, sd 30fps
PMC x-tac M193, (5.56), avg 2997fps, es 111fps, sd 35fps
Hand loads (.223), avg 2946fps, es 48fps, sd 15fps
My general purpose training load.
LC brass
CCI #41 primers
55g Hornady FMJ, Col 2.200
CFE223 27.0g (thrown with a hornady powder thrower)
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rc … Surprisingly the 4198 did not work out for you .
When I first bought my Ranch Rifle ( 187 series ) I got better than acceptable & practical accuracy. When loading my own with IMR 4198, I scored mighty high in our Club’s “ Military Rifle Shoot”. The scoring was done by a Marine Veteran , using the Marine scoring perimeters. BTW the loads I was using was a half grain under Max. No malfunctions throughout the match.
When I first bought my Ranch Rifle ( 187 series ) I got better than acceptable & practical accuracy. When loading my own with IMR 4198, I scored mighty high in our Club’s “ Military Rifle Shoot”. The scoring was done by a Marine Veteran , using the Marine scoring perimeters. BTW the loads I was using was a half grain under Max. No malfunctions throughout the match.
Ike Clanton
New member
Speer data shows a 2.5 grain difference between 223 and 556 for the powder I use. I don’t go to max but I load lake city 556 brass a grain higher than the 223 max and below the 556 max without issue.
I'm not sure if the original poster's question wasn't rhetorical and meant to be a criticism of the Lee manual, but I'll assume it was meant as a legitimate question. "Ike Clanton" came close to the answer, but I'll try to be more direct. The answer to "why would a manual not have info for the 556 round?" is: most of them do. The Hornady 11th edition, the Speer 15th edition, and the Sierra 6th edition all have separate sections for reloading data for the .223 remington and for the 5.56 NATO / or AR15 rifle.
Now for the advice to the original poster: get yourself a real reloading manual.
Now for the advice to the original poster: get yourself a real reloading manual.
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totaldla said:
There is an interesting example of how even the professionals have been tripped up by 5.56/223 pressure differences. Those Western loads produce 13% higher pressure than the standard 223 Rem MAP because someone at Western believed the SAAMI conformal transducer system would match the readings produced by the CIP transducer system. They don't. I called Western about this in about 2017, IIRC. The ballistic tech I spoke with confirmed they had used a SAAMI-type conformal transducer and SAAMI reference loads to calibrate in producing those pressures. If they wanted to match what the CIP measures as a maximum load, they needed to use a CIP reference load's CIP-rated pressure to calibrate.
The difference is neatly illustrated by the U.S. military. The first image is for M193, and you can see they list the exact same pressure difference between the copper crusher and transducer that SAAMI does, so you know their measuring systems tracked the ratio of the two measurement types the same as the SAAMI systems do. That's important because when you get to M855, which is our military's interoperability ballistic twin to the European SS109, you see the 55,000 PSI by copper crusher rating goes to 58,700 PSI by transducer, and not to the 62,366 PSI number used by the CIP. Only the European measuring systems would read it that high.
So Western took a pressure that should have been 58,700 PSI on their conformal transducer, or about 7% over standard 223 Rem SAAMI MAP, and instead gave us 13% over SAAMI MAP, and which would read somewhere around 66,260 psi in a CIP measurement. Oops!
But here's what is useful about that mistake. Given the difference between a SAAMI test barrel chamber and the NATO test barrel chamber produces about a 2,000-3,000 PSI difference, even plopping a round of M855 into a SAAMI test chamber barrel will not reach the pressure Western loaded to for that list. And if, after a decade, Western hasn't had reports of gun problems with those loads that caused them to issue warnings and withdraw the list, then guess what? The guns handle those pressures. They are, after all, still below the SAAMI proof pressure range (73,500 to 78,500 psi). Just be aware they will accelerate throat erosion, the same as anything making higher temperatures and pressure will do. I don't recommend them for that reason, but it is interesting to see how they been hanging around.
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@Unclenick: I always admire and respect your technical knowledge. I'm glad you came on board and maybe you can help me with something. This discussion on .223 and 5.56 incompatibility and the dozens of others which I've read at the Firing Line, all seem to focus primarily on chamber pressures. For the life of me, I can't understand why chamber pressures are even relevant. When I look at the breeching and locking system on my .223 Savage 11 and Winchester 70, and then compare them with an AR-15 or mini 14, there is no way those bolt actions are weaker than the AR or mini. If a 5.56x45mm NATO, 55 grain FMJ does not blow up an AR, then it surely will not cause a failure in most modern bolt actions. The real incompatibility problem between 5.56 NATO and commercial .223 is the chamber throat and the bullet length, not chamber pressure. You can make the argument that that chamber pressure dangerously spikes with longer bullets and the shorter throat of the .223, but that is a "tail wagging the dog" argument. Those pressure spikes are the symptom and not the cause. The real question is: What is the maximum bullet length which can be used in .223 chamber, while using 5.56 data? I've had no problems with 55 grain bullets in 5.56 NATO commercial loadings (and I'm not recommending it), but I'm not sure where the ceiling is beyond that bullet length.
Anyway, you're the expert, and you are always good at explaining and sorting things out. I'll leave this with you.
Anyway, you're the expert, and you are always good at explaining and sorting things out. I'll leave this with you.
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Thank you.
If you have a bolt gun that is sold in 223 Rem and 308 Win (or similar) with the same receiver and the same barrel profile, it is difficult to argue the thicker metal the chamber and barrel will have and the lower head contact area the bolt face will have when chambered in the 223 Rem will not withstand more pressure (though that will erode throats faster). I think this is at least part of the reasoning behind the CIPs' decision to use the higher SS109 military pressure numbers for their 223 Rem chamber pressure than the M193 numbers SAAMI uses for the cartridge.
Even though I read that specialty ammunition reasoning somewhere, I can't say I've personally run into such loads, nor have I seen drawings for any. The military loads have a couple of constraints that would make such ammo unusual. For one, the cartridge's overall length cannot exceed the standard maximum because it has to fit and feed in magazines and on belts. The second is that for full interoperability, they want ballistics to be consistent with NATO ammunition, and that means muzzle velocity and ballistic coefficients need to be a good match. Otherwise, sight systems will lose calibration, and tracer round trajectories will mismatch (though they already do at longer ranges). Matching the ballistic coefficient means keeping nose forms close to matching for a given weight and base shape, and when you add that constraint to the maximum length constraint, you wind up with the same fit the various ball ammo has.
Perhaps someone who has seen special ammo for spec ops groups will have run into a non-SAAMI-chamber-compatible load. Experimental ammo could certainly have a non-universal fit. It seems to me at least one of the military marksmanship units was rolling long-range rounds with the 80-grain SMK before the TMKs came out, and those would have stuck out to extra COL, which was OK since they would be single-loaded for the 600-yard line and beyond. But those long-nosed bullets still fit the tighter match chambers.
If you want to check for differences, I would use the Hornady bullet comparator but substitute the Sinclair stainless adapter inserts because they are cut closer to the dimensions of a standard throat, contacting the bullet much further down near the shoulder, which is what meets the lands. Just measure some of the ball ammo loads you know work, and then measure any other 5.56 ammo you run into before shooting it. If you find some whose bullet shoulders are further forward, use some caution. If you have the Hornady overall length gauge, you can pull a bullet from one round and use it with the gauge to see how far off the lands it is. I would think 0.020" or more should be OK. The other approach would be to pull bullets on a handful of rounds and measure the powder charges. Reseat the bullet on the heaviest charge, then knock the others down in 1-2% increments until you are 10% lower. Then start shooting them from that low end, watching for pressure signs or anything that makes you uncomfortable. With the bolt gun, obviously, you can watch out for sticky bolt lift as a sign.
If you have a bolt gun that is sold in 223 Rem and 308 Win (or similar) with the same receiver and the same barrel profile, it is difficult to argue the thicker metal the chamber and barrel will have and the lower head contact area the bolt face will have when chambered in the 223 Rem will not withstand more pressure (though that will erode throats faster). I think this is at least part of the reasoning behind the CIPs' decision to use the higher SS109 military pressure numbers for their 223 Rem chamber pressure than the M193 numbers SAAMI uses for the cartridge.
Even though I read that specialty ammunition reasoning somewhere, I can't say I've personally run into such loads, nor have I seen drawings for any. The military loads have a couple of constraints that would make such ammo unusual. For one, the cartridge's overall length cannot exceed the standard maximum because it has to fit and feed in magazines and on belts. The second is that for full interoperability, they want ballistics to be consistent with NATO ammunition, and that means muzzle velocity and ballistic coefficients need to be a good match. Otherwise, sight systems will lose calibration, and tracer round trajectories will mismatch (though they already do at longer ranges). Matching the ballistic coefficient means keeping nose forms close to matching for a given weight and base shape, and when you add that constraint to the maximum length constraint, you wind up with the same fit the various ball ammo has.
Perhaps someone who has seen special ammo for spec ops groups will have run into a non-SAAMI-chamber-compatible load. Experimental ammo could certainly have a non-universal fit. It seems to me at least one of the military marksmanship units was rolling long-range rounds with the 80-grain SMK before the TMKs came out, and those would have stuck out to extra COL, which was OK since they would be single-loaded for the 600-yard line and beyond. But those long-nosed bullets still fit the tighter match chambers.
If you want to check for differences, I would use the Hornady bullet comparator but substitute the Sinclair stainless adapter inserts because they are cut closer to the dimensions of a standard throat, contacting the bullet much further down near the shoulder, which is what meets the lands. Just measure some of the ball ammo loads you know work, and then measure any other 5.56 ammo you run into before shooting it. If you find some whose bullet shoulders are further forward, use some caution. If you have the Hornady overall length gauge, you can pull a bullet from one round and use it with the gauge to see how far off the lands it is. I would think 0.020" or more should be OK. The other approach would be to pull bullets on a handful of rounds and measure the powder charges. Reseat the bullet on the heaviest charge, then knock the others down in 1-2% increments until you are 10% lower. Then start shooting them from that low end, watching for pressure signs or anything that makes you uncomfortable. With the bolt gun, obviously, you can watch out for sticky bolt lift as a sign.
@Unclenick: I may not have been clear about bullet length. I meant just that: the length of the bullet, not overall loaded cartridge length. I always thought the compatibility problem was the longer 70 and 80 grain .224 bullets bumping too quickly into the rifling due to the shorter throat or leade or the .223.
I do appreciate your detailed answer. It will take me awhile to digest it all.
I do appreciate your detailed answer. It will take me awhile to digest it all.
If you keep the same cartridge overall length and have the same ogive, then there will be no difference in bullet jump to the throat. The extra bullet length then will simply be seated deeper into the case, as is done with tracer rounds. The illustration at the top of this page shows it. It includes two tracers: one to match the non-NATO M196 round's trajectory and the other to match the M855 round's trajectory.
It was a serious question. Now what do you consider a real manual?