conflicting load data

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conflicting load data

Postby Slugger » Sat Jan 23, 2016 10:17 am

What do yall do when you find conflicting load data. I'm getting ready to do some .223 loads with IMR 4198 and hornady 55gr SP for my 20" varmint rifle chambered in .223 wylde.
my issue is I really don't know where to start. The Hornady manual shows start load of 17.4 gr with a max load of 20.0 gr. The Nosler data is starting at 19.5 going up to 21.5 and the sierra (AR-15 DATA) starts at 20.1 and goes to 22.5 . I have noticed that it seems Hornady data seems to almost always be on the more conservative side with most of their data. So after seeing all of that I went to the IMR data and they show max of 21.5 I'm thinking I will just start 10% below the IMR data and work up in .5 gr increments from there. what do you think?
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Re: conflicting load data

Postby Al in Mi » Sat Jan 23, 2016 12:32 pm

better safe and start low.
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Re: conflicting load data

Postby Jim in Houston » Sat Jan 23, 2016 12:57 pm

Or you could pick the low end of where they all overlap. I would do this rather than take an arbitrary 10% off one of the recommendations. But start low is always good advice.
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Re: conflicting load data

Postby m113103 » Sat Jan 23, 2016 1:17 pm

Are they using the same cartridge cases, primers and test barrels? Some mfg's use undersized chambers and bores to represent highest pressure situations. Some use real barrels. The last thing is the bearing surface of the bullet used. IMHO use the data for the bullet brand that you are using and load 5 at the starting load and check for pressure. What method are you using for checking pressure? Are you using new cases to develop loads? If all you want is plinkers then use once fired brass and keep the pressure low. If you want loads near the max IMHO use new brass and go up on the charges slowly and measure every one accurately and keep good notes. :P :P :D :D
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Re: conflicting load data

Postby Slugger » Sat Jan 23, 2016 3:07 pm

I have no intentions of pushing MAX pressures. I'm using matching headstamp range brass. I weigh each charge and sort cases by length. I'm just wanting to work up an accurate load for punching paper and yotes. I will start at the Hornady starting point of 17.4 and go up from there picking the best load for my gun. I was just confused on why the start load from one manual would be within .3 grains of the max in another. I understand that different barrels will produce different pressures as well as air temp, different batches of powder ect. I just didn't realize it would be such a dramatic swing.
Thanks
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Re: conflicting load data

Postby Hoot » Sat Jan 23, 2016 5:45 pm

FWIW, QuickLoad modeling software agrees with Nosler, based on loading them to 2.26 COL. What you can not add to the calculation though is what kind of primer you are using. That can account for the differences from one source's range to the other. I do believe Hornady bases many of their loads on the Winchester Small Rifle primer, which like Remington 7 1/2's are pretty peppy compared to say Federal or CCI plain Jane primers. Not to distract from the topic with primer debates.

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Re: conflicting load data

Postby lungingturtle2 » Sat Jan 23, 2016 6:39 pm

Please be aware that military headstamp brass is thicker brass which decreases internal volume and will drive pressures up. Max loads of some bulkier powder in commercial .223 cases can over flow military cases.
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Re: conflicting load data

Postby m113103 » Sat Jan 23, 2016 7:55 pm

Good reading on the subject Handbook of Metallic Cartridge Reloading by Ed Matunas. He was a ballistic tester for Winchester. :P :P :D :D
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Re: conflicting load data

Postby m113103 » Sat Jan 23, 2016 8:04 pm

When using range pick-ups sort by headstamps and weight. When using different headstamps or other componets drop 10% and work up. It is a pain but the only safe way to do it ( keep good notes ). That way you only go thru this one time with each lot of brass. :P :P :D :D
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Re: conflicting load data

Postby Hoot » Sat Jan 23, 2016 11:02 pm

m113103 wrote:When using range pick-ups sort by headstamps and weight. When using different headstamps or other componets drop 10% and work up. It is a pain but the only safe way to do it ( keep good notes ). That way you only go thru this one time with each lot of brass. :P :P :D :D


Being the rifle range coordinator at my local club, I get lots of LEO practice brass pickups. Believe it or not, the heaviest deprimed brass award goes to PMC. Yes PMC, not LC or IMI. Go figure...

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