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Posted: 2/13/2017 8:38:59 PM EDT
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Hey guys quick question before I brew up some loads...
Relaoading for a 16" ar10 168gr Hornady BTHP Varget Cci 200 primers 2.8 COAL So I originally was using federal once fired brass (fed .308 blue box ammo). I found my best groups at 42.2gr of powder. I now have a glut of once fired ZQI 7.62x51 brass. Head stamp MKE14 (all the ZQI brass I prepped was checked and grouped by year). In terms of load development, should I be using data for .308 or for .308 Winchester Serice rifle? My Hornady manual #9 has load data titled .308 win (test rifle is a model 70 bolt gun) and also load data titled ,308 Win Service rifle (m14 test rifle). Somewhere I read that commercial brass vs NATO brass you need to reduce your max load by 1gr. Bolt vs semi auto you reduce the load by 1gr as well. Thanks for the Sanity Check guys |
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I agree with dryflash3.
I also suggest that you weigh the casings and compare them to your FC casings. At least this will give you an idea of how different they may be. The service rifle data is for the M1A/M14 rifle. While the data should be ok for your AR it wasn't developed with the AR platform in mind. Motor |
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I haven't used MKE or ZQ1 brass but would wager that it's comparable to Lake City as far as internal capacity is concerned. Lake City 7.62x51mm brass weighs close to 180 grains empty and unprimed. It requires a 2.0 whole grain reduction of powder charges.
.308 brass is all over the place as far as weights and internal capacities are concerned. If your brass weighs 175+/- grains empty and unprimed I would treat it like Lake City. Only Winchester commercial brass can be relied on to have really high internal capacity. Remington commercial is a close second. Mixing brass and using the same charge across the board is a recipe for poor accuracy. Pick one brand and stick with it. Foreign surplus 7.62x51mm can have even less capacity than LC. I suggest anyone loading surplus brass should buy the old NRA book, now out-of-print, called "Semi-Auto Rifles - Data & Comment". It's available online from used book sources. It contains two articles regarding loading Lake City 7.62x51mm brass and Sierra Match King bullets. They fired close to 1000 rounds of hand loads through a Universal Receiver and pressure testing barrels. Accuracy as well as copper units of pressure were recorded using the U.S. military testing protocols and directed under the supervision of Wm. C. Davis Jr.. Mr. Davis was probably the greatest ballistician of the 20th Century. I have used his data for close to 30 years with outstanding results in both Lake City and IMI brass. This referenced data is the singular best source I know of for loading surplus military brass in .308. |
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Quoted:
I haven't used MKE or ZQ1 brass but would wager that it's comparable to Lake City as far as internal capacity is concerned. Lake City 7.62x51mm brass weighs close to 180 grains empty and unprimed. It requires a 2.0 whole grain reduction of powder charges. Fyi, it was my experience the zq1 is closer to win than lc. |
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Quoted:
Fyi, it was my experience the zq1 is closer to win than lc. Quoted:
Quoted:
I haven't used MKE or ZQ1 brass but would wager that it's comparable to Lake City as far as internal capacity is concerned. Lake City 7.62x51mm brass weighs close to 180 grains empty and unprimed. It requires a 2.0 whole grain reduction of powder charges. Fyi, it was my experience the zq1 is closer to win than lc. This is a timely question since I just checked the H2O capacity of some MKE 14 earlier tonight. It was 55 grains so I'd put it about in the middle of win and LC or about the same as hornady |
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Thanks for the responses guys. Sorry life got in the way and haven't been back to check on the topic. I'm going to start over and do a work up. I've got a ton of the brass so I hope it holds up to a few loadings before the primer pockets loosen.
The ammo from factory "patterned" out of my ar! .50/round I took a gamble and lost |
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Use 10 cases from each lot.
Fill the 10 federal cases with water. Fill the 10 cases in question with water. Weigh the water from each of the 10 federal cases and get an average weight. Weigh the water from each of the 10 cases in question and get an average weight. Using the known case/water weight (federal) as the 100% standard. Find out what percentage the water weight from the cases in question is compared to the 100% federal cases. Exapmle: The avg water weight from the 10 federal cases is 300gr The avg water weight from the 10 cases in question is 280gr The cases in question hold 7% less water. This is telling you you should reduce your load in the federal cases by 7% to get the same load in the cases in question. Weighing the water from 10 different cases will also tell you how well they were make. |
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Dang!!!
Forgot 1 important step. Whatever you do for case prep to the federal cases to get your pet load. You should do to the federal cases and the cases in question. Meaning: If you full length size them to reload for your ar load. Then resize all the brass. Trim all the brass to the same length. Leave the spent primers in the primer pockets. Basically you want to make both brands of cases uniform size and length. Them measure the internal volumes of both brands. I would still do the ladder test that dryflash recommended. This will give you a cross checkfor your #'s + fine tune your load to that lot of brass. |
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3221,
How do you come up with this reduction or increase in the load to correspond with difference in case capacity? I can see trying to duplicate conditions between different casings but seriously doubt that a 5% difference in capacity is going to make any real difference in pressure. Plus how do you know that changing the powder charge by the same percentage of the difference in capacity of the case is actually doing what you are suggesting it does? So using you method if I was shooting 50gr of powder and this was a maximum load if I found casings that were 10% less capacity I could then go 10% or 5gr over maximum. Hmm. I don't think I'll be trying that. Motor |
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Quoted:
3221, How do you come up with this reduction or increase in the load to correspond with difference in case capacity? I can see trying to duplicate conditions between different casings but seriously doubt that a 5% difference in capacity is going to make any real difference in pressure. Plus how do you know that changing the powder charge by the same percentage of the difference in capacity of the case is actually doing what you are suggesting it does? So using you method if I was shooting 50gr of powder and this was a maximum load if I found casings that were 10% less capacity I could then go 10% or 5gr over maximum. Hmm. I don't think I'll be trying that. Motor |
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Quoted:
Yeah it was late and I wrote "less" when I meant more. I still wouldn't go 10% over maximum because the casing had 10% more capacity. I would like to see the technical data that supports this theory. I don't believe there is any. Motor |
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While 308 can be quite forgiving, I have found very similar results with com cases.
Any suspected military cases may require a slight load adjustment from a safety point of view. Mostly however from an accuracy point of view you may have to adjust your charge. In general military cases never gave me the best accuracy,if that's what you are looking for. Later John PS forgot to douple space my diatribe 
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