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Mixed brass, case capacity and QuickLoad
https://www.waguns.org/viewtopic.php?f=74&t=81615		 Page 1 of 1
Author:  MadPick [ Mon May 29, 2017 1:41 pm ]
Post subject:  Mixed brass, case capacity and QuickLoad
I've been doing a lot of .223 loading the last few days, putting together another batch of prairie dog rounds. I'm using mixed brass, 26.0 grains of Hodgdon Benchmark, 50-grain Hornady Z-Max bullets, Wolf small rifle primers and an OAL of 2.24".

As I load, most of the rounds look roughly like the one on the right in the photo below, where you need to look down into the case a bit to see the powder because it comes to roughly the bottom of the neck:

Image

However, occasionally I'll see one like this, with the powder almost to the top of the case:

Image

(And yes, that is still the correct powder charge -- I verified it.)

Every single one of the cases that had the powder level that high had S&B head stamps. So, I checked the water capacity of one of them and it was 29.6 grains. I checked a couple of Lake City cases for comparison, and they held 30.2 grains of water. So . . . what does that mean?

Well, per QuickLoad it means quite a lot. And yes, I'm aware that this is a pretty hot load to begin with. :bigsmile: For reference, the maximum spec chamber pressure for .223 Remington is:

Per SAAMI: 55,000 psi
Per CIP (European): 62,000 psi

So, if I input all of my numbers with the Lake City brass into Quickload, it tells me that my chamber pressure is 59,082 psi and my predicted muzzle velocity with a 24" barrel is 3421 fps:

Image

And if I lower the case capacity to the S&B number, the chamber pressure jumps to 62,179 psi -- above even the European max! Predicted muzzle velocity with a 24" barrel is 3455 fps.

Image

And yes, I've measured muzzle velocity in the 3440 fps range from my 24" AR-15 with this load, so the predicted velocities above are right on.

My conclusions?

- Case capacity matters, especially if you already have a hot load.
- I've shot a lot of this particular load in the past, including from S&B brass, so I'm going to shoot everything that I loaded.
- I'm going to sort out the S&B and I won't use for this load anymore; I'll save it for lighter plinking loads.

Any thoughts?
Author:  SAGELA [ Mon May 29, 2017 5:03 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
CPI/NATO spec of 62,000 PSI data are available on Western Powders website.
If I were loading to NATO spec I'd want a NATO leade in my rifle's barrel.
And I'd be looking at case capacity (as you suggest) to prevent fudging the spec.
Particularly when you only get 34'/s in doing it.
Author:  MadPick [ Mon May 29, 2017 5:22 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
SAGELA wrote:
If I were loading to NATO spec I'd want a NATO leade in my rifle's barrel.


Does that mean, "I'd want a rifle chambered in 5.56, not .223"?
Author:  SAGELA [ Mon May 29, 2017 9:17 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
MadPick wrote:
SAGELA wrote:
If I were loading to NATO spec I'd want a NATO leade in my rifle's barrel.


Does that mean, "I'd want a rifle chambered in 5.56, not .223"?


These days it usually means a Wylde chamber - most of those are marked ".223 Remington/5.56 NATO"
Instead of just extra freebore, it ramps up from freebore to lands/grooves a tad more gradually.
Author:  SixPointEight [ Sun Jun 04, 2017 9:10 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
SAGELA wrote:
CPI/NATO spec of 62,000 PSI data are available on Western Powders website.
If I were loading to NATO spec I'd want a NATO leade in my rifle's barrel.
And I'd be looking at case capacity (as you suggest) to prevent fudging the spec.
Particularly when you only get 34'/s in doing it.

Agreed. 62k PSI is acceptable for 5.56 loads, though I don't often like to push the envelope with mixed brass of unknown loadings.

Interesting how thick that S&B case head must be. Surely it can handle the extra pressure

Sent from my SAMSUNG-SM-G920A using Tapatalk
Author:  Sinus211 [ Sun Jun 04, 2017 10:02 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
That Benchmark powder is semi extruded. I know you've verified the case volume difference but I would think it's also possible that the stick powder in some of those cases settled better than others and some are just sitting a little high. Did you try covering the case mouth and flicking the case to see if the powder settle down lower when agitated?
Author:  MadPick [ Mon Jun 05, 2017 5:34 am ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
Yeah, it will settle a bit ... but the comparison you see above is real, as neither case has been shaken and the S&B cases consistently looked like that.

The issue isn't that the S&B cases are "too full," just that they are more full than the other cases.
Author:  VantageReloading [ Mon Jun 05, 2017 7:27 am ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
How many SB cases do you have available? Load a set (10 minimum) of those along with another set of your other cases and head to the range to chronograph for any specific velocity spread.

As has been mentioned, the pressure isn't so bothersome (don't leave your ammo can in the sun?) but I would be more concerned with velocity spread and the effect on accuracy.

I am also curious to know if the sb cases chronograph true to the QL calibrations.

:AR15firing:
Author:  MadPick [ Mon Jun 26, 2017 7:52 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
VantageReloading wrote:
How many SB cases do you have available? Load a set (10 minimum) of those along with another set of your other cases and head to the range to chronograph for any specific velocity spread.


Image

All right, I found ten matching S&B cases and ten Lake City 2008 cases. First I checked the average case capacity of all ten cases of each kind:

S&B: 28.7 grains of water
LC 2008: 30.25 grains of water

Here are the QuickLoad predictions with my standard load of 26.0 grains of Benchmark, a 50-grain Z-max bullet and 2.24" OAL with Wolf magnum primer. First, the LC 2008:

Image

And the S&B:

Image

Note the pressure prediction: 58,864 PSI for the LC 2008 and 67,576 PSI for the S&B. Again, the SAAMI maximum is 55,000 PSI and the CIP (European) maximum is 62,000 LCP.

I went to the range yesterday and tested the velocity of the rounds using my 20" Mossberg MVP. I got data for all ten of the LC 2008 rounds, but the Labradar didn't catch the last two S&B rounds . . . so the data below is based on eight rounds of S&B.

LC 2008 velocity
QL prediction: 3,288 fps
Actual: 3,250 fps, standard deviation 12.7

S&B velocity
QL prediction: 3,384 fps
Actual: 3,337 fps, standard deviation 14.5

So . . . conclusion? I dunno. QL predicted a 96 fps difference, and I saw an 87 fps difference. So that's pretty close, I think? The actual numbers were off by roughly 40 fps, but in my mind that's pretty close for a computer prediction, considering all of the variables involved.

Oh, and here are the cases, with S&B on the left and LC 2008 on the right. QL failed to predict the pierced primer. :bigsmile:

Image
Author:  Sinus211 [ Mon Jun 26, 2017 10:15 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
Nice craters in some of the s&b primers. That's pretty f'd up that they're using brass with lower case volume on such a high pressure round. That could end up being pretty dangerous for those who load at the top end of saami recommendation.
Author:  VantageReloading [ Mon Jun 26, 2017 10:16 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
Fascinating - thanks for sharing the results. In no particular order:

Quick load doesn't perfectly approximate chamber pressure, howevee I can't help but notice the rounds with SB cases that are predicted to be over pressure have Significant primer cratering

SD of mid teens for a wolf primer is solid. Good prep work and loading practices for that kind of result.

You haven't calibrated QL for the temperature you faced if you went to the range on Sunday (95*F?) when QL bases calculations on 70*F by default. You'll need to adjust the powder Ba value to calibrate for your lot number of benchmark.

Your 87fps difference vs 96fps difference on the prediction is half of a standard deviation of either of your loads, which renders that value statistically irrelevant if you aren't bothered by the small sample size (18 rounds total). I would say that's "spot on".

Which load shoots better? Better yet, what is the average POI? Do either measures change at all when you mix a magazine?

Keep it coming! You're just getting started ;)
Author:  MadPick [ Mon Jun 26, 2017 10:23 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
VantageReloading wrote:
You haven't calibrated QL for the temperature you faced if you went to the range on Sunday (95*F?) when QL bases calculations on 70*F by default. You'll need to adjust the powder Ba value to calibrate for your lot number of benchmark.)


I don't know how to do that. icon_eek

VantageReloading wrote:
Which load shoots better? Better yet, what is the average POI? Do either measures change at all when you mix a magazine?)


Yeah, I didn't try to test accuracy . . . mostly because although I know I can shoot a good group, I don't have enough confidence in my shooting to give you something statistically significant with only 10 rounds of each type.

VantageReloading wrote:
Keep it coming! You're just getting started ;)


:ROFLMAO:

Well, I have no more unloaded Z-max bullets . . . so that's my easy out. :bigsmile:
Author:  TwizDD [ Thu Jul 06, 2017 3:28 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
Fuck all this reloading nonsense! Did no one notice, the Sasha Grey reference!? :rofl9:
Well done Steve..well done! :thumbsup2:

Aaaannnndddd... Noooow... back to our regularly scheduled reloading nonsense! :bigsmile:

Oh by the way... :hitit:
Author:  PMB [ Thu Jul 06, 2017 3:38 pm ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
TwizDD wrote:
Fuck all this reloading nonsense! Did no one notice, the Sasha Grey reference!? :rofl9:
Well done Steve..well done! :thumbsup2:

Aaaannnndddd... Noooow... back to our regularly scheduled reloading nonsense! :bigsmile:

Oh by the way... :hitit:

That is Sasha Grey? At first I thought Steve just went ahead with his transformation. and still :hitit:
Author:  sportsdad60 [ Tue Jul 11, 2017 7:28 am ]
Post subject:  Re: Mixed brass, case capacity and QuickLoad
Nice report out Steve! Damn! It's science! I love it!
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