Grant's Loads

Reloading info for the 5.7x28mm

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Rapier1772
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Re: Grant's Loads

Post by Rapier1772 » 17 Feb 2014, 12:30

Grant disappears for a while at a time; most of us usually don't know why until he comes back.

All we can do is be patient & hope all is well with him. He's got friends here if he needs them.
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Tripwire
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Re: Grant's Loads

Post by Tripwire » 14 Jun 2014, 18:22

"BLUE DOT

45gr Barnes TSX. Trim: 1.135" OAL: 1.575" Primer: CCI 400

6.6gr: 1839fps 6.7gr: 1857fps 6.8gr: 1872fps 6.9gr: inconclusive 7.0gr: 1900fps 7.1gr: 1918fps 7.2gr: 1931fps 7.3gr: 1943fps 7.4gr: 1955fps 7.5gr: inconclusive 7.6gr: inconclusive 7.7gr: 1975fps n=1

My sample sizes were small, and there was so much variation in some of these loads that I had to throw out too many outliers. None of the 7.5gr and 7.6gr loads got over 1952fps. From 7.5-7.7, there was a lot of flattening and extrusion. One case had a deep black crater. For practical purposes I would place the max at 7.4gr. However, I did not feel I was in any real danger shooting 7.7gr. Interestingly, as the charge moved towards the max, the empty cases began ejecting almost straight behind me on the right."

*******
I had a primer blow first shot at 7.0 grains:
Once fired pristine brass., exact same load, hand weighed charge, FSN MK2, **1999 fps over my chronograph**, ~3900ft elevation, 75F, 55% humidity. 7.4 grains is WAY too hot from my results, even 7.0 is over Max.
*******





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Rapier1772
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Re: Grant's Loads

Post by Rapier1772 » 14 Jun 2014, 19:33

Smart move, starting well below the max. Thanks for the info.
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grimmond
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Re: Grant's Loads

Post by grimmond » 14 Jun 2014, 21:32

Tripwire wrote: I had a primer blow first shot at 7.0 grains:
Once fired pristine brass., exact same load, hand weighed charge, FSN MK2, **1999 fps over my chronograph**, ~3900ft elevation, 75F, 55% humidity. 7.4 grains is WAY too hot from my results, even 7.0 is over Max.
Those are interesting results. When I ran the same strings, mine were within 40fps of grants. Probably because I used an EFK barrel w/EA HD spring. I also figured max at 7.4gr.. I have now fired about 30 rounds at 7.4gr to verify my initial results, and they matched. When I took it higher the primers started flattening. At 7.6gr I started having a stiffer recoil. At 7.7gr I had 1 pierced primer. I stopped at 7.8gr because I had a case neck split on the first shot.

I am wondering if the Blue Dot formula has changed some that could account for this difference.
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Rapier1772
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Re: Grant's Loads

Post by Rapier1772 » 14 Jun 2014, 22:45

Tripwire, what are you using for a scale & when was it last calibrated?
I'm not saying that is the problem, just a potential cause of the discrepancy.

It could also be as grimmond suggested & they changed their formula.
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Tripwire
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Re: Grant's Loads

Post by Tripwire » 16 Jun 2014, 05:31

RCBS charge master 1500, I recalibrate with test weights every time I power up.

Here's the kicker: My Blue Dot is Lot 296 from June 16, 2009, purchased in 2012. Ill rework the string from 6.5gr to see if I get similar results wand post here.

This just illustrates the importance of working up your own loads in your own gun and being conservative.

shopsmart
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Re: Grant's Loads

Post by shopsmart » 16 Jun 2014, 17:40

Got a ceiling fan on in the shop/room? I find I get a varience of .1 or more if it is going. Tends to degrade even over a minute. Even on the lowest setting.

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