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Posted: 2/18/2015 9:18:28 PM EDT
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I'm planning to run a large batch of .223 in the near future using H335, CCI 450 primers and M193 projectiles. Intending to use 25.5gr as a max, reduce by 10% and work up in .5 gr increments to start with. These will be primarily for plinking/practice fired through ARs with 5.56 chamberes.
The question I have is due to the fact that my brass is all mixed headstamps. I've sorted everything out by headstamp and have taken 10 piece samples from each type, weighed the empty case, filled it with water, weighed it again and then determined the case volume in grains of water. (See average case volumes below sorted low to high). At what point should I reduce my load to maintain safe pressures due to reduced case capacity or can these be lumped in together? Approximately 90% of my brass falls between 31.28 and 31.69. Should I be concerned with reducing my load for cases in this range? Or am I over thinking this a bit? 
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The answer is, it depends... If you plan on taking the load into the warm region, then you are best off to test with your extremes. That isn't advisable unless you really know you are not going to throw conditions even hotter later on.
It doesn't sound like you are interested in flirting with disaster, so as long as you keep some margin that type of case volume variation won't mater. If you are worried about the pressure, test with those extreme cases since you have already identified the case volumes. Getting H335 to mimic a decent load isn't going to give you any trouble if you are paying attention to the details, as you obviously are.... You probably will find you have ample margin if you are using a standard bbl length and velocity goal. |
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Knowing what I know about this load, I have the following recommendations. 1) Treat PMP totally separate, it's heavy brass with less internal volume. I load it 2 grains lighter than those other cases. Don't go past 22.0 grs with this bullet/powder combo. 2) I wouldn't go past 24.5 grs since you have mixed cases. I have gone higher, but with headstamped matched cases. 3) If it were me, I wouldn't use the FC cases. I sell/trade them off. 4) Work up very carefully. |
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Here is what I would do, YMMV.
Separate out the PMP, Fiocchi and FC. Not for capacity reasons alone. Start your load work up using the Hornady brass. It has the least capacity of the remaining. Or, if you insist on using the PMP, start your load work up with it. Switching to cases with higher capacity will not be a problem as far as pressure is concerned. Quickload predicts an increase in pressure from 31.74 to 30.4 of 4K psi. Also your target of 25.5gr is over Max according to Hodgdon. |
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Thanks for the advice folks. Starting with the Hornady makes sense to me and I'll go ahead and set the PMP, Fiocchi and FC aside. If I use any of those three I'll work up a separate load for each type. Just out of curiosity what's the reasoning behind not using the Fiocchi or FC besides volume?
Steve4102, you're correct, Hodgdon lists 25.3 MAX for a Speer soft point. Not sure where I got the 25.5. By the way, if anybody is interested in my case weight data I'd be happy to send my spreadsheet along. |
| So right after I replied earlier I was straightening up in the gun room and found another bucket of S&B brass that I'd missed the first time around. Weighed 10 rounds of this and it came out to an average case capacity of 30.91 gr of water. So I think I now have a plan. I'm going to work up a load with the IMG 5.56 brass since I have a lot more of that than the Hornady, set the FC and PMP aside, and work up a load for the S&B since I have enough of that to be worth doing separate. The Hornady and Fiocchi I'll either set aside or load separately. |
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All brass was once fired and untrimmed.
And speaking of trimming, I just got my Dillon 650 set up for trimming with their trim motor. Wow that makes that chore easy and quick. Very accurate as well, set it up with Dillon's case gage and I'm getting 1.750" +/- .001". |
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