300 Blk; IMR4227; 125gr SMK
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Primer: CCI #400
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COL: 2.210"
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Powder Charge: 16.5gr
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Velocity: 1852fps
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Platform: AAC Handi-Rifle 16" 1:7 twist
I based on Sierra load data for H4227, with the assumption that H4227 = IMR4227 which I've heard is the case. Exceptionally clean powder burn, good accuracy. However, even though this is near the bottom end of the charge range, my primers came out pretty flat, and the velocity was about 100 fps lower than expected. I likely won't be pursuing this load further.
Posted Mar 19, 2015, 5:18 PM UTC
58
That's interesting, I am using 125 SST with 17.7 IMR4227 and I'm not seeing pressure signs in the primers. This is out of an AR platform.
I have some fired cases left over from this load I'll check when I get home this afternoon. I've been loading a lot more pistol than rifle lately, so it's entirely possible I was being a primer flatness wuss when I noted the results.
Here is what I was getting. Did yours look much like this?
Yea, mine is looking a little different
Hm, I wonder if it's down to a difference in seating depth? The results here are a bit confusing.
I'm getting a COL of 2.110 +/-