5.56 loads hotter than 223 maxed?

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I was doing some research on what powder would give my hunting round the most punch and came across this article: http://www.loaddata.com/articles/pdf...nt5lowres1.pdf

I found it very helpful and saw that the author was getting great results from Win-748 for the Sierra 65 grain GameKing. I decidedto go ahead and get a pound of it. Upon getting back to the house, I double checked the author's load with Hodgdon's website. I found that the author was above the max per Hodgdon's site. But, Hodgdon does not allow for the differences between 5.56 and 223 pressures. Accurate Powder does and lists several loadings with increased powder charges above the 223 max loads.

What does everyone else do for 5.56? I'm wanting to say that I'm going to call this one a $30 learning experience and get some Accurate powder and use their 5.56 data instead of venturing into the territory of "Well, this guy that wrote an article on the internet said this was OK."

Does anyone go over the listed 223 loads for 5.55 rounds? I know my gun will take the extra pressures, but I don't want to experiment. Figured I'd ask yalls take on this.

P/S, the article was very good other than the over max load data and worth the read IMO.
 
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5.56 has a higher chamber pressure by SAAMI standards. If your gun is chambered for 5.56 I would shoot loads at that level. 223 & 5.56 are two different rounds sharing the same cartridge case. I do not shoot 5.56 in my gun that is chambered for 223 Rem.
 
The first thing to do is make certain you have a 5.56 chamber & throat, and not 223. The best you can hope for when making that mistake is blown primers.
 
I use .223 data and work up til I find the most accurate load. I don't KNOW what the difference in velocity is between the 2 (which is what I assume you mean by 'punch') but from what I have researched it appears to be around +50fps for 5.56 to 200yds then around +50fps for .223 to 500yds. This, to me, is negligable. I don't think a critter gives a darn whether it was .223 or 5.56 that just went through his vitals at 2400 or 2450fps. Also, to me, it stands to reason that if you FLR 5.56 brass using .223 dies then you now have .223 brass....all of this gives me a headache so I just go with the KISS principle. YMMV
 
I chrono'd some 55gr. NATO out of my 16" carbine earlier in the week and got 3030fps. I've been unable to get anywhere near that velocity with "book" loads. I've loaded my own for 40+ years and still don't feel comfortable boosting listed charges to get NATO velocities.

Because I'm a hunter/target shooter, accuracy has always been more important to me than speed. That doesn't mean that velocity doesn't enter into the equation, but it's down the list after accuracy, firearm function, and bullet performance.
 
Even though my AR is chambered for 5.56, I stick with published 223 loads.
My standard load is 26 gr of Varget under a 55 gr FMJ.
Very accurate & 2900+ fps.
 
Turns out the over max load from Hodgdon is in my Lyman manual! Lyman starts at 24.7 and tops out at 27.5 grain of W 748. Hodgdon tops out at 25 flat. Sierra's data starts at 24.3 (I think) and tops out at 25.9 grains. This is a lot of disparity!

I loaded 40 rounds in a 'ladder' starting at 24.7 grains and going up to 26.8 grains. Five rounds each. I plan on testing them tommorow evening out of my 16" AR (Stag). I will be keeping detailed notes and looking for accuracy. The gun will have a bore snake run through it (dry) between the five shots.
 
The low end rounds shot great but only gave me 2500 fps. I found another accuracy node at 25.9 grains which gave me just under 2800 fps. I loaded up a bunch at that and called it good. Its still over Hodgdon's max but it is right at Sierra's max and well under Lyman's max. Powder seems to leave a lot of carbon behind. When I've shot this pound up, I will likely look for a different powder just for the cleanliness of it.
 
You need to "tweek" those loads now by moving the bullet out (seating the bullet out further).

I do test loads the same way (ladder) with a powder & look for the most accurate load. Then I use that load & do another "ladder" test by loading 5 ronds of ammo & then moving the bullet seating die out a 1/2 turn & loading 5 more & so on until I either reach the maximum length for the mags or the lands & grooves depending on what I want to use the load for.

You'll watch the groups tighten up when you hit the sweet spot for the amount of bullet jump (freebore) that your bbl/bullet combo likes.
 
.223 VS 5.56

The issue with the difference between 5.56 and .223 brass is case volume. My understanding is that 5.56 military brass is thicker than .223 commercial brass and therefore the case volume will be less. If you load a .223 case and a 5.56 case with identicle volumes of powder the pressure in the 5.56 case should be higher due to reduced case volume. When working up a load for my 5.56 I started at 10% below max and went up in .1 grain increments looking for signs of excessive pressure. When the primers started to flatten out I backed off.

The difference in the chamber dimensions between the .223 and the 5.56 is the amount of leade. The leade or the amount of distance from where the chamber ends and the rifling starts is longer in a 5.56 chamber. This allows military ammo of possibly varying dimensions to be chambered and fired without any problems. The only issue is that the longer the jump the bullet has to make to get to the rifling the more it could affect accuracy. If you fired a long 5.56 round in a short .223 chamber the bullet could be jammed into the rifling causing high pressures on ignition. I have fired both .223 and 5.56 in my rifles with no issues.
 
TAC or H335 will give you more velocity in a .223 pressure load. I shot H335 with 53 SMK's. Good powder, had a big muzzle flash. I havent tried TAC yet. Ramshot has info for .223 and 5.56 but unless you are looking for longer range shots .223 loads will get you there. My normal load is 24 grains of Varget and 77 SMK's, shooting out to 600 yards.

As far as the original question, 5.56 has a higher chamber pressure. Some .223 brass is 5.56 labeled .223 and loaded to a lower pressure. Thats why you need to work up a load for the brass you are shooting. The biggest difference in the chamber is in the throat and the 5.56 chamber is a hair longer.
 
Forrest r said:
You need to "tweek" those loads now by moving the bullet out (seating the bullet out further).

I do test loads the same way (ladder) with a powder & look for the most accurate load. Then I use that load & do another "ladder" test by loading 5 ronds of ammo & then moving the bullet seating die out a 1/2 turn & loading 5 more & so on until I either reach the maximum length for the mags or the lands & grooves depending on what I want to use the load for.

You'll watch the groups tighten up when you hit the sweet spot for the amount of bullet jump (freebore) that your bbl/bullet combo likes.
Click to expand...
I have to deal with magazine limitations on seat depth. I want semi-auto for those rapid kill all the hogs you can shooting. It seems a COL of 2.26 is about the max my mag will do and still feed reliably.
 
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