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Posted: 7/23/2021 9:35:32 AM EDT
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Does this little of a FPS change seem correct? Should I try a different primer, maybe a magnum, to burn more of the powder so it will run cleaner? Load: Berry's 200 gr spire point Accurate 1680 CCI small rifle # 400 COAL 2.23" Edited to add: crimped using Lee factory crimp die 10.5" with pistol length gas system. Without suppressor. Powder charge / FPS (average of 5-shots) 9.5gr / 1,072 10.0 gr / 1,076 I didn't, but I should have recorded all 5-shots. I will check these loads again another day. I noticed more than expected unburnt powder. This photo is after 10 rounds. The velocity didn't increase as much as I thought it would between the two loads. When I ran these through a chronograph there was some overcast, but the other loads I tested that day increased with each powder charge as you'd expect so I don't think the overcast threw off the measurements, but maybe. |
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Hard to say without seeing individual shot data. Also five shot strings aren't very good sample sizes. I do at least 10 unless you're looking for very rough load data points. 1680 is definitely not a clean powder. It's just very gaseous and works well for 300 BLK subs where cycling could otherwise be an issue, like when unsuppressed. |
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That is sort of weird. I used 1680 with 200gr Maker Rex (all copper bullet) and got: 9.5 gr 880 fps 9.8 gr 931 fps 10.2 gr 979 fps Ultimately I switched up to 220gr bullets. For plinking I am using 220 gr Berry pushed buy IMR 4227 (very quiet) and for hunting I am pushing 220 gr Maker REX with the Accurate 1680. |
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Quoted: What is a cleaner powder for suppressed loads than 1680? CFE Black? A1680 is meant to burn at a higher pressure than subsonic 300 Blackout ammunition runs at. Supersonic and subsonic 300 Blackout loads run at completely different chamber pressures, but enough gas at the gas port is still required to cycle the action. |
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