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Rifles, Reloading, Optics, Equipment
Reloading
More powder, less velocity - how is this possible?
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<blockquote data-quote="atl5029" data-source="post: 1250530" data-attributes="member: 84273"><p>Well I learned a couple of things today...</p><p></p><p>1. My problem was definitely the fact that my chrony was way too close and possibly not level. I set it up much farther out than last time and shot some Remington UMC 120 grain 300 Blackout though it and was getting expected velocities betweem around 2200 FPS. Shot my 260 AI loads with 49 and 49.5 grains of H4831SC. 5 rounds at 49 grains averaged 2896 FPS and 5 rounds at 49.5 grains averaged 2909. This is what I would expect.</p><p></p><p>2. IMR4831 must throw a hell of a fireball compared to H4831SC. I also shot 5 rounds loaded with 46 grains of IMR4831, and my first two shots gave me unrealistic values in the mid 1300s. I moved my chrony even farther out and it gave me good readings again. I'm guessing the gasses are getting into the chrony and doing weird things. The 3 rounds that gave good readings averaged 2830 FPS.</p><p></p><p>All 3 of these loads shot into a nice group, which is always good.</p><p></p><p>3. The third thing explains a lot of my previous troubles....old IMR4831 is a lot hotter than new IMR4831. When I first started load development for this rifle, I used an old canister of powder I bought from an old timer with some other reloading equipment. It was an old metal canister, probably made in the 70's if not earlier. That same load of 46 grains gave me about 2950 FPS previously, and did again today. With that powder I was also getting really flattened primers and other pressure signs. Who knows if the powder in that canister was even really 4831. Lesson learned...when buying powder from people you really don't know, be 110% sure you know what you're buying. </p><p></p><p>All in all though it seems load development is back on track. Hope you guys find this experience to be useful knowledge</p></blockquote><p></p>
[QUOTE="atl5029, post: 1250530, member: 84273"] Well I learned a couple of things today... 1. My problem was definitely the fact that my chrony was way too close and possibly not level. I set it up much farther out than last time and shot some Remington UMC 120 grain 300 Blackout though it and was getting expected velocities betweem around 2200 FPS. Shot my 260 AI loads with 49 and 49.5 grains of H4831SC. 5 rounds at 49 grains averaged 2896 FPS and 5 rounds at 49.5 grains averaged 2909. This is what I would expect. 2. IMR4831 must throw a hell of a fireball compared to H4831SC. I also shot 5 rounds loaded with 46 grains of IMR4831, and my first two shots gave me unrealistic values in the mid 1300s. I moved my chrony even farther out and it gave me good readings again. I'm guessing the gasses are getting into the chrony and doing weird things. The 3 rounds that gave good readings averaged 2830 FPS. All 3 of these loads shot into a nice group, which is always good. 3. The third thing explains a lot of my previous troubles....old IMR4831 is a lot hotter than new IMR4831. When I first started load development for this rifle, I used an old canister of powder I bought from an old timer with some other reloading equipment. It was an old metal canister, probably made in the 70's if not earlier. That same load of 46 grains gave me about 2950 FPS previously, and did again today. With that powder I was also getting really flattened primers and other pressure signs. Who knows if the powder in that canister was even really 4831. Lesson learned...when buying powder from people you really don't know, be 110% sure you know what you're buying. All in all though it seems load development is back on track. Hope you guys find this experience to be useful knowledge [/QUOTE]
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Reloading
More powder, less velocity - how is this possible?
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