AR15 223 Reloads Terrible SD and ES.

[JFrank]

From post #1

btw, I shot some factory IMI 556 and they had VERY tight ES and SD.

 

[JFrank]

Yes. I worked up on all three powders and while I did not document each one specifically, they were all bad. Always had at least one at a very high velocity and one at a low velocity.

This speaks volumes towards the rifle/rifles just not playing well with the combination of components you’re trying to feed them.
Q- how are you seating these primers?
Q- Any chance you are crushing them ?

 

[Hartkopf]

This speaks volumes towards the rifle/rifles just not playing well with the combination of components you’re trying to feed them.
Q- how are you seating these primers?
Q- Any chance you are crushing them ?

Frankford Arsenal hand primer. I know what it feels like to crush a pistol primer because they're so soft.

I chamfered the crimp out of the cases and then cleaned the pockets but the CCI 450s were very hard and very hard to seat. It still never felt like I crushed them, just tight all the way. The shape of the primer and the radius at the corners looked completely normal when I was done. I seated 100 CCI 400s last night and could tell the difference. Much less force needed. (I'll try to test these tomorrow)

I'll keep an eye on this because the 450s did give me more hell than any other primer I've ever seated.

 

[JFrank]

This may shed some light, the 450’s are actually listed as smaller

 

[Keyfer 55]

I have an old ar 223 barrel I find it more accurate than my 5.56 nato.

 

[Metal God]

I ran duplicate load development test with 55gr FMJ-BT and H-335 , Only thing different was the primers . One test was using CCI#400 the other was using #450 .

The test with the mag primers had MUCH worse ES/SD at every charge increment then the standard primers . On this test I did not crip the bullet and the theory is that the extra power/force the mag primers have is unseating/moving the bullet before the powder fully gets burning . This resulted in a inconsistent initial burn or start pressures from shot to shot . Poor plinking case prep likely contributes do to less consistent neck tension/bullet hold from case to case .

Although I've not ran another duplicate test with crimped bullets , I have noticed that over time and other testing a firm crimp when using mag primers does have better ES/SD using H-335 powder FWIW that is 25.5gr . This "may" be the reason you are getting better results with the Factory NATO ammo because they do have a pretty firm crimp which will hold the bullet back just a tad to allow the powder to really get burning before bullet starts it's jump .

 

[Hartkopf]

Ok I finally got around to more testing and the #450 Mag primers definitely caused higher spreads. Standard #400s cut the ES in half. I then increased the charge up into 556 range and that also reduced the ES. The numbers were still not great (around 37 to 40) but at least it was in a more normal range, as opposed to near 200. All of my testing was done with budget FMJ bullets but I did load a small batch of Hornady 55gr soft point which tightened the ES into the 20s. I shot a quick group and they were right at 1 moa on a terribly windy day with a crappy rest.

Thanks to all for the advice. I'm new to rifle loading so I learned a thing or three. The high ES probably never would have hurt anything but I wanted the fundamentals to be somewhere in the ballpark before I shot 1000s of rounds through my favorite AR.

 

[kmw1954]

Two years ago when I first started with rifle shooting and reloading with a Savage 223 to use for my first season shooting in a rifle league I did extensive load work trying to find what works and what doesn't. Shot 62gr and 69gr bullets from a number of makers and then also shot loads with 4 different powders. Hundreds of rounds shot over a chrono. I was trying to achieve the same results some of my friends were getting with there match grade custom barrels and receivers. HaHa, that was a joke on me! I will admit my loading skills improved tremendously and my loads reached a level that wasn't close to what my friends were doing and I became disheartened. My average ES was hovering around the 40-60fps with a few at times that would drop into the 20's.

With these loads I was shooting sub MOA at both 100 and 200yds so I gave up with the chronograph. No one was able to ever provide me with a reasonable explanation for the high ES. I since moved to a new Savage model 12 Varmint barrel and my ES is steady about 24fps, and that is with CCI400, CCI450 and RP 7 1/2 primers.

So then just recently I came across a topic on loading the 223 and Chrono numbers at the Accurate Shooter forum and found the consensus seems to be the 223 is not conducive to Low numbers and they attribute it to the long narrow powder column and poor powder ignition.

 

[denton]

Ok I finally got around to more testing and the #450 Mag primers definitely caused higher spreads. Standard #400s cut the ES in half. I then increased the charge up into 556 range and that also reduced the ES. The numbers were still not great (aroundr 37 to 40) but at least it was in a more normal range, as opposed to near 200. All of my testing was done with budget FMJ bullets but I did load a small batch of Hornady 55gr soft point which tightened the ES into the 20s. I shot a quick group and they were right at 1 moa on a terribly windy day with a crappy rest.

Thanks to all for the advice. I'm new to rifle loading so I learned a thing or three. The high ES probably never would have hurt anything but I wanted the fundamentals to be somewhere in the ballpark before I shot 1000s of rounds through my favorite AR.

Sounds like you are on the right track. A couple of thoughts:

Try annealing your brass. Some factory brass is annealed better than others. Work hardened brass will inflate variation.

If you are taking SD or Range from a small sample, fagetaboutit. With fewer than about 50 rounds, your estimate of variation can be way off and non-repeatable.

I would not use a 400 primer in my AR. It's too easy to get "pierced" primers. 450 or 41 are more appropriate.

Good luck, and remember, we are doing this for fun.