Ok- total confusion on reloading 5.56 vs. .223

S

Snolan4571

Member
Joined
May 5, 2014
Messages
44
Reaction score
10
Location
Minnesota
Hi everyone,

Guess the post title says it all. I have been reloading for years but have never been so confused on such a small but yet complicated task.

I have a S&W M&P 15T chambered of course for 5.56

Below are my questions.

1. Going into all of the load books are so confusing when it comes to the actual projectile. Of course they all list mostly their own manufactured projo's.

What about the person who goes out to "bullet heads" and buys a 1000 of .224, 55gr FMJ. Which projectile listed do you start with?

2. Now on to a more confusing question. I really understand the difference between a .223 and a 5.56. The throat lead is different as well as in some instances the internal geometry of the actual case due to thickness differences.

OK- so "most" published data is for the .223 and I have decided to start my reloading project for AR's with the following

55 gr FMJ, H335 powder, CCI41 primers and LC 13/14 cases but do also have about 450 Federal .223 cases.

OK now for the actual issue/confusions on this part. The 5.56 case was designed to withstand higher pressure for the M-16 vs the civilian .223 case. BUT considering the inside dimensions can be less is the 5.56-

Does this mean that say a starting load for my rifle using the 5.56 case with 24.5 gr of H335 will be significantly higher pressure than the same amount in a .223 case?

Does this mean that a max load safely fired in my rifle using H335 and a .223 case may not even indicate over pressure but same load fired in a 5.56 case could be catastrophic?

3. This is also confusing to me. Just read where the published OAL for .223 for a given bullet should be 0.010 less when using a 5.56 case.

I am confused considering everything I read show the external dimensions to be exactly the same for both cases.

4. Is there ANY publication that really goes into the sciences of reloading JUST for the .223 AND the 5.56?

I would like to hear from individuals that have been loading both the .223 and 5.56 cases and really understand the differences.

I am at the point of thinking I will just begin my loads .5 gr above the min for both and then working up each of the different case type/caliber to reach the most accurate in each.

Thanks in advance for your knowledge and experience, and most importantly your patience in guiding me.

Steve
 
Register to hide this ad
All of this depends on whether or not you intend to use max loads. I use commercial brass and 223 data for loads for my AR. If you are just looking for loads of average accuracy that will cycle in the AR then it doesn't really matter. If looking for match accuracy then you would need to pay attention to case weight and type to maintain consistency. Either way I would start with the "starting/minimum" load and work up. if you are going to use military brass then work those up separately. Load data for most 55gr FMJs should be fine with any brand of bullet.
 
The only differences between 5.56 and .223 Rem are:

5.56 Military is loaded to slightly higher pressure levels.

The 5.56 chamber has a longer throat to off-set the higher pressure.

Some types of 5.56 are loaded with heavier bullets than .223.

Because of the heavier (longer) bullets the 5.56 has a faster twist rate.

Other than these the two cartridges are identical. Unless you are loading bullets heavier than 55 grains, or trying to squeeze the absolute last FPS from your loads, simply use published .223 data. Don't worry about bullet brand, while this may make a small pressure difference it will still fall within 5.56 pressures, regardless of which brand bullet you use. This is particularly true if you are using cannelured bullets and seat to the cannelure.
 
If you buy military 5.56 brass you will find that it is longer. I have found some as much as .040 longer than 223! It depends where it came from. I keep my military brass separate from the 223. But I trim to the same length and use the same recipe for both. I don't use bullets over 68grs. and I don't hot rod my loads. I try to stay around 2900 to 3000 fps.
 
Work up your loads with lc brass. Stop when you are accurate not at max. If this is below book max for 223, you are ok to go on in Fed. brass. If you are seating 1/10" from the lands regardless of cannelure keep your brass separate.
 
The only difference between 223 and 5.56 cartridges is that 5.56 can be loaded to higher pressures . . . because 5.56 chambers are designed for it. Other chambers (eg Wylde) are also designed to hold 556 cartridge pressures.

But 5.56 cases are thicker, right? Not necessarily. You will find charts showing that "military brass" has lower case capacity than 223 brass. But when you measure actual brass from different manufacturers (water capacity), you find that many "223" cases have less capacity than "military" cases, may in fact differ from themselves from batch to batch, and will differ from what's shown in any chart at one time or another.

Can I fire 223 in a 5.56 chamber? Yes.

Can I fire 5.56 from a 223 chamber? You should not because the cartridge may be charged to a higher pressure than a 223 cartridge, and the tighter chamber will exacerbate that.

What spec should I reload to? Regardless of their chamber, most folks simply reload to 223 specs and work up a load that's accurate watching for pressure signs along the way. IOW, they ignore 5.56 differentiation. IIRC, Hodgdon does not even publish data under 5.56. Hornady 9 shows counter-intuitive, small, or absolutely no 223/5.56 difference in min/max for most powders.

Finally, H335 meters very well and isn't a bad choice for 55gr bullets. Using Hornady 55gr FMJBTw/c OAL 2.200" (case crimped (if done) at the cannelure), most people find accuracy between 24.3gr and 25.0gr. Two of my rifles (Wylde chamber) like 24.9gr, my 223 chamber shoots 24.3 best but much prefers different bullets and powders.
 
I am fairly new to ar 15's I have had my m15 sport for a little while
at the range I notice a rather big difference between the .223's and the .556 rounds the .556 has much more power than the .223 so much that a shooter next to me said he sees a muzzle flash with the .556 that didn't occur with the .223, I had each loaded alternately in the magazine for a comparison. I also load my own but cant find any recipes for the .556 separate from the .223. I separate my brass and so far go with a little higher load in the .556 rounds but they don't seem to have the same kick as the factory ammo
 
Keeping it simple

For a new production AR style rifle the difference between 223 and 5.56 is very similar to buying 12 large eggs versus buying a dozen large eggs.

I use Accurate Arms 2230 powder, a mid-range powder charge for 50 gr HP bullets, and shoot that load in 5 different rifles accurately without a problem. I use mixed brass and don't sort headstamps. I make sure to separate range brass (military vs commercial) to ream military primer pockets to remove the crimp.

I won't bore you with details about cleaning, tumbling, case length, and trimming brass.


EDIT: A chronograph is the only thing that can tell the difference between a 3100 fps or 2900 fps bullet. Neither a target or prairie dog knows the difference. A prairie dog does know the difference between 223 and a 25-06 -- there is less to pickup if you use a 25-06.
 
Last edited:
Use 223 data for both, you'll be fine. Dies are set to size the case for your rifle.
 
The Hornady #9 manual has separate sections for loading .223 and 5.56X45.
 
Only primers I've ever blown have been when I chose to shoot M193 in a tight match .223 chamber. Since the primers were crimped in, I can't imagine what the pressure was. That might have explained the marks caused by the brass extruding into the ejector.
 
gregintenn said:
223=556.

556=223

Don't over think it.
Click to expand...

Good advise! when I started loading 5.56, 223..what ever you want to call it..I was in the same boat way over thinking every detail. After loading some rounds the veil lifted and it's no different than any other round. My advice would be to buy a case gauge, Wilson works for me. I load cheap 55gr. bullets with H335, W844 or W846 for plinking. Plenty accurate for me and besides, my Son owns his own AR and turns it into a bullet hose anyway.
 
See gregintenn, believe it.
I've never even shot an AR-15 let alone reloaded it. But your problem is obvious, you are waaaay over thinking it. You are wanting some gold standard, etched in stone answer. It doesn't exist. Different companies test in different ways, again, no standard. You will find the same variations in practically all calibers. Load 'em up any way you want to within the guidelines and shoot away. The answer you seek isn't in the manuals, it's at the range.
 
I agree with not overthinking it. However Hornady, Sierra, and Accurate manuals have separate sections for 556 chambered AR style rifles. The 556 data is 'hotter' than the 223, up to a full grain or more for max loads in some instances. I have had no problems shooting max 223 loads in my 556 and Wylde chambered ARs. I only worked up one load with the 556 data and it did show some pressure signs at the top end. I'm happy just sticking to 223 data.
 
Last edited:
Thanks for the info. I figured I was out in the twilight zone with my thinking but like I said ask ten people and you get 15 answers.

S
 
Just to add to the confusion wait until you decide to build your first AR. Are you going to purchase a barrel chambered for .223, 5.56, or Wylde? So, what feed ramps do you want on your barrel extension, M4 or M16? Does that new upper feature M4 or M16 feed ramps? As I am discovering all if this does matter. Fortunately I do have help in avoiding the pitfalls but have concluded that NATO set this whole ball of wax up this way to prove that even intelligent people can be reduced to a complete state of confusion by tweaking a civilian caliber by just a little bit. Yeah, another conspiracy theory so bring in Muldair and Scully.

BTW, I've found this thread quite useful as I will start reloading for the .223/5.56 once I get my own particular ball of confusion sorted out.
 
NJM15 said:
I am fairly new to ar 15's I have had my m15 sport for a little while
at the range I notice a rather big difference between the .223's and the .556 rounds the .556 has much more power than the .223 so much that a shooter next to me said he sees a muzzle flash with the .556 that didn't occur with the .223, I had each loaded alternately in the magazine for a comparison. I also load my own but cant find any recipes for the .556 separate from the .223. I separate my brass and so far go with a little higher load in the .556 rounds but they don't seem to have the same kick as the factory ammo
Click to expand...

This is more a function of powder burning rates and charactaristics than power. Pressures may be similar but the 5.56 powder's burn trail is longer.
 
You must log in or register to reply here.

Similar threads

elpac3
.22 jet bullet seating
Replies
8
Views
717
M29since14
M
W
Wasp waisted reloads revisited
Replies
9
Views
701
Forrest r
F
P
Overpressure signs in a Model 66-3 with starting load data
2
Replies
38
Views
2K
HKSmith
H
chief38
My experience & opinion as to costs of reloading now days.
2 3 4
Replies
76
Views
4K
Lance Boyle
L
chief38
I HAVE FINALLY RAISED THE SURRENDER FLAG IN RELOADING 45ACP
3 4 5
Replies
92
Views
6K
Greyman50
Greyman50

Latest posts

Back
Top