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Posted: 6/29/2013 1:28:52 PM EDT
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I fully intend to keep updating this thread as I develop more loads and make more tests with AR-COMP powder.
Haven't been able to find much data on AR-COMP, and even less with my weapon set-up...so I am developing my own load data to work from. Today was the first day. Please Note: The data for the loads that I post here are all for a 16" RECCE 5.56 barrel with a 1:8 twist and with a suppressor. Didn't have much time due to storms, but I timed it between downpours. I had originally intended on running 4 batches starting with 22gr of powder and working up - 10 shots per batch, but the sky was black so I changed it up a bit just to get some data. The Ammo: 55 grain Hollow Point Flat Tail Case Trimmed length - 1.746" (Presized) Overall Length - 2.222" (after sized and seated) Powder - Alliant's AR-COMP Primers - CCI 400 Weapon platform - 16" RECCE Barrel in 5.56 with a 1:8 twist (Suppressed) Batch 1: 25.3grs of AR-COMP Powder Shot 1 - 3039ft/s Shot 2 - 3028ft/s Shot 3 - 3027ft/s Shot 4 - 2995ft/s Shot 5 - 3028ft/s Shot 6 - 2984ft/s Average ft/s on Batch 1 = 3016 ft/s Batch 2 25.5 grains of AR-COMP Powder Shot 1 - 3001ft/s Shot 2 - 3004ft/s Shot 3 - 3033ft/s Shot 4 - 3049ft/s Shot 5 - 3059ft/s Shot 6 - 3091ft/s Average ft/s on Batch 2 = 3039 ft/s I had doubts about using AR-COMP on the lighter bullets, but it looks like I'm good to go. I can maintain an excess 3,000 ft/s from a 16" barrel (suppressed) with the lighter 55 grain rounds - and that is frigging awesome for the longer distance shooting. Have to wait for the storms to let up to chrony the 62 and 68 grain bullets. Thoughts on my methodology? |
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Quoted:
Looks like it is working out for you. Are you checking the condition of the brass afterwards too? How did the primers look? The primers are seated perfectly. There is zero issue there at all. None of the cases appear to be deformed, or neck split or otherwise out of shape. I'll be putting them on the micrometer in a few and measuring the before and after trim length for the cases. It will be interesting to see if they grew. This is a 5.56 barrel...so I'm not sure what to expect there. But visually, they look great. EDIT: - Just measured the spent brass. The original trim length was 1.746" What I didn't expect was to get a shorter case length... They measure out now at 1.743"... Is this normal? Obviously this could be accounted for in 2 different ways of measuring the brass, and I can assume to say there was zero change in the length. However I fully expected to see SOME growth... What gives? |
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Quoted:
Quoted:
Looks like it is working out for you. Are you checking the condition of the brass afterwards too? How did the primers look? The primers are seated perfectly. There is zero issue there at all. None of the cases appear to be deformed, or neck split or otherwise out of shape. I'll be putting them on the micrometer in a few and measuring the before and after trim length for the cases. It will be interesting to see if they grew. This is a 5.56 barrel...so I'm not sure what to expect there. But visually, they look great. EDIT: - Just measured the spent brass. The original trim length was 1.746" What I didn't expect was to get a shorter case length... They measure out now at 1.743"... Is this normal? Obviously this could be accounted for in 2 different ways of measuring the brass, and I can assume to say there was zero change in the length. However I fully expected to see SOME growth... What gives? It will grow/stretch when you size it again. |
| 25.3gr is way too much! You should give the rest of that AR-Comp to me before you hurt yourself! Seriously though I'm tinkering with it lately myself. Chrony wasn't cooperating last trip out but I'm getting around 2630 fps with 69gr SMK's using 23gr of AR-Comp. That's .2gr below max according to Sierra, so I'll try to push it a little faster but I'm getting excellent accuracy so far. Anyone else have a source for load data? |
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]Today, I conducted another chrony test. This time, I was using the 50gr Hornady V-MAX.
The Ammo 50 grain - Hornady V-MAX Polymer Tip Boat Tail Case Trimmed length - 1.746" (Presized) Overall Length - 2.240" (after sized and seated) Powder - Alliant's AR-COMP Primers - CCI 400 Weapon platform - 16" RECCE Barrel in 5.56 with a 1:8 twist (Suppressed) Batch 1: 23.5gr of AR-COMP Powder Shot 1- 2825 Shot 2- 2826 Shot 3- 2798 Shot 4- 2839 Shot 5- 2835 Shot 6- 2776 Shot 7- 2798 Shot 8- Chrono Error - data discarded Shot 9- 2791 Shot 10- 2856 Average ft/s on Batch 1 = 2816ft/s with a standard deviation of 26.32 Batch 2 24 grains of AR-COMP Powder Shot 1- 2926 Shot 2- 2894 Shot 3- 2901 Shot 4- 2891 Shot 5- 2906 Shot 6- 2913 Shot 7- 2895 Shot 8- 2905 Shot 9- 2889 Shot 10- 2880 Average ft/s on Batch 2 = 2909ft/s with a standard deviation of 29.40 Batch 3 24.5 grains of AR-COMP Powder Shot 1- 2967 Shot 2- 2916 Shot 3- 2958 Shot 4- 2948 Shot 5- 2924 Shot 6- 2911 Shot 7- 2953 Shot 8- 2968 Shot 9- 2944 Shot 10- 2899 Average ft/s on Batch 3 = 2938ft/s with a standard deviation of 24.55 Batch 4 25 grains of AR-COMP Powder Shot 1- 2982 Shot 2- 3017 Shot 3- 2023 Shot 4- 2987 Shot 5- 2974 Shot 6- 3025 Shot 7- 2995 Shot 8- 2985 Shot 9- 3013 Shot 10- 2972 Average ft/s on Batch 4 = 2997ft/s with a standard deviation of 20.39 Batch 5 25.3 grains of AR-COMP Powder Shot 1- 3029 Shot 2- 3046 Shot 3- 3049 Shot 4- 3046 Shot 5- 3052 Shot 7- 3049 Shot 8- 3032 Shot 9- 3039 Shot 10- 3033 Average ft/s on Batch 5 = 3042ft/s with a standard deviation of 8.256 It is interesting that the instant I broke and maintained the 3,000ft/s mark on batch 5, the standard deviation tightened up TREMENDOUSLY. This tells me that this is my most accurate round when I go to the range. The others had too much of a deviation to be "the" accurate load for this round. Thoughts? |
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