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PLEASE USE PUBLISHED MANUFACTURER'S DATA FOR YOUR LOADS. USE THIS ONLY FOR REFERENCE.

Conditions:

Date: 8/16/2014
Location: Cheney Outdoor Shooting Range, Pretty Prairie, KS
Range: 100 yard
Temp: 86 deg F
Humidity: 65%
Pressure: 29.8 in
Wind: 0-5mph from NNE
Sky: Clear
Gun: AR-15, 16" BBL, 1:8 twist

Components:

Powder: Benchmark
Primer: CCI 400
Bullet: Nosler .224" 60gr Spitzer Ballistic Tip
Brass: LC @ 1.750"
COAL: 2.250"

Results (5 shots each charge)

Load: 21.5gr
Avg Vel: 2449
SD: 32.8
ES: 76
Group: 1.014"

Load: 21.7gr
Avg Vel: 2492
SD: 50
ES: 120
Group: 1.059"

Load: 21.9gr
Avg Vel: 2485
SD: 36.9
ES: 101
Group: 1.264"

Load: 22.1gr
Avg Vel: 2536
SD: 21.7
ES: 54
Group: 0.684"

Load: 22.3gr
Avg Vel: 2543
SD: 15.9
ES: 39
Group: 0.964"

Load: 22.5gr
Avg Vel: 2523
SD: 17.5
ES: 48
Group: 1.722"

Load: 22.7gr
Avg Vel: 2569
SD: 44.8
ES: 108
Group: 1.259"

Load: 22.9gr
Avg Vel: 2602
SD: 16.9
ES: 36
Group: 1.888" (this surprised me b/c a low SD and ES)

Load: 23.1gr
Avg Vel: 2646
SD: 32.5
ES: 89
Group: 2.121"

Load: 23.3gr
Avg Vel: 2636
SD: 32.5
ES: 78
Group: 1.181"

Load: 23.5gr
Avg Vel: 2644
SD: 22.1
ES: 58
Group: 1.894"

Comments:

Published data went from 21.5gr to 23.5gr. Nosler load data says 22.5gr of Benchmark is their most accurate load, for Benchmark itself and for all other powders they tested. They noted 3048fps at 22.5gr. I saw about 525fps less than that. As I approached 23.5, I noticed the primers beginning to flatten out. I know CCI primer cups run a little thin, so I felt pretty comfortable going to max published load. 21.9gr shows lower average velocity, but lower SD and ES than 21.7gr.

I think my AR likes the heavier Sierra's better, I'll do some more testing with the other powders I have to confirm this.

I think I'll follow this up with a little more detailed workup (10 rounds each) from 22.0gr to 22.5gr.

What do you guys think?
 
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