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Old March 5, 2012, 11:41 PM   #1
Arrowhead
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.223 Varget & Magnum primers?

How much should I back off the powder when using CCI 450 primers in an AR? My Hornady manual lists 23.5 grs a max load with a 75HPBT.
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Old March 6, 2012, 12:12 AM   #2
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I came to understand that BR primers were the hottest in primers, If you have experience reloading the only safe way is to start at the min and work your way up while checking for signs of pressure and accuracy.
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Old March 6, 2012, 04:56 AM   #3
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Yeah, you want to back off from max at least 10% and work the load up with the different components looking for pressure signs along the way. So in this instance I'd back up to 21 grains and do a ladder workup in .2 grain increments. FWIW, when I do workups I usually end up finding a sweet spot before I reach max anyway.
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Old March 6, 2012, 09:57 PM   #4
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FWIW, when I do workups I usually end up finding a sweet spot before I reach max anyway.
Same here but for example I want to creep to closer max loads only for most of the info on ballistics I've seen all of those rounds on the charts at max speed and for me to use some charts without a big ordeal and I like the hornady's ballistic charts gives me the energy at those distances.
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Old March 6, 2012, 11:02 PM   #5
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You don't want to back off from Max at all. You need to Start your load development at the "Start" charge and work up checking for signs of high pressure. Just backing off from a published max is a guess at best and a bad idea. A Chrony ism't a bad idea either.
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Old March 6, 2012, 11:16 PM   #6
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You don't want to back off from Max at all. You need to Start your load development at the "Start" charge and work up checking for signs of high pressure. Just backing off from a published max is a guess at best and a bad idea. A Chrony ism't a bad idea either.
How exactly does reducing a load by 10% and working up qualify as a guess? Reducing loads by 10% and working up will put you at or below starting loads anyway.
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Old March 6, 2012, 11:23 PM   #7
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In the old days they didn't publish a minimum, you had to do a little math and back off from max to start.

Any small rifle primer will work safely. Some may be more accurate than others for you, or you may not notice.
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Old March 6, 2012, 11:50 PM   #8
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In the old days they didn't publish a minimum, you had to do a little math and back off from max to start.
I'm glad I'm not the only one who remembers those days.
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Old March 7, 2012, 08:42 AM   #9
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How exactly does reducing a load by 10% and working up qualify as a guess? Reducing loads by 10% and working up will put you at or below starting loads anyway.
Sorry, I misunderstood and misread the above posts. I read, back off 10% and consider that your new max, not work it back up. My apologies.
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Old March 7, 2012, 05:05 PM   #10
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Sorry, I misunderstood and misread the above posts. I read, back off 10% and consider that your new max, not work it back up. My apologies.
Got it, no worries.
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Old March 7, 2012, 09:26 PM   #11
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Mag primers in a 26gr case with Varget? I don't get it. Mag primers give significant added pressure with the attendant bolt thrust in an auto. At 40 a thousand, why risk it?
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Old March 7, 2012, 09:32 PM   #12
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I load for a bolt action, and have had good luck using standard CCI small rifle primers. I have used Winchester Primers with the same loads, and the results were too close to tell a dirreance.

Then again I am not shooting an AR, nor do I (or likely will) shoot in exteem weather. If it is under 45 outside I am staying it. Here in this part of Texas it will usualy warm up in a day or two. If it is hotter than 95 in the shade I will either shoot early in the morning, or in the evening after it has cooled down. I have other hobbies that can be doen inside.

I would say when in doubt. Go load up a few from starting load up to the load you were using. If you see pressure signs before reaching the load you were using, or accuracy falls off go with the one that gave the best accuracy.
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Old March 8, 2012, 10:25 AM   #13
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Mag primers in a 26gr case with Varget? I don't get it. Mag primers give significant added pressure with the attendant bolt thrust in an auto. At 40 a thousand, why risk it?
Floating firing pin in the AR requires a thicker primer cup for safety, although some folks have gotten away with some brands of small rifle primers (CCI 400's come to mind). But small rifle magnum primers or "milspec" primers are recommended for ARs and other rifles with floating firing pins (M1As, Garands, etc).

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