Finished up some testing today. Pretty interesting results I think. Thought I would share. Colt ar 15, Faxon 16in gunner profile barrel, 4-14x44 optic (for testing, not regular use) Larue MBT 2 stage 4lb trigger, on bags.
I watched the Hornady podcast about sample sizes being too small. It basically boiled down to the concept that you need to shoot 20 rounds per group to get reliable data. Whether that be zeroing your rifle, doing chronograph testing, or group size testing.
The other interesting thing that was noted was that, while you should shoot 20 rounds, it does not have to be 20 straight. Shoot how you use it. for a hunting gun 3 round. the idea being 1 round to hit the animal, 2nd round in case you had a bad shot, 3rd round in case everything went wrong. so fire 3, let the gun cool, repeat.
Heres the podcast if your interested https://www.youtube.com/watch?v=QwumAGRmz2I
So I loaded up 140rnds. 20rnds, 7 groups. each group had 0.003 variation in seating depth. went out and shot it at 100yds.
Since I'm in an AR platform, I estimated 20 rounds at once would be worst case. About 2 seconds per shot, enough time to get a good steady sight alignment and squeeze the trigger. gave the barrel a 10min cool down between groups.
1 4.09moa (mean radius 1.18moa)
2 3.98moa (mean radius 1.08moa)
3 2.64moa (mean radius 0.78moa)
4 4.04moa (mean radius 0.86moa)
5 3.36moa (mean radius 0.87moa)
6 3.59moa (Mean radius 1.06moa)
7 3.79moa (mean radius 0.93moa)
Considering this was fairly rapid fire, the barrel got quite hot, and the bullets were bulk fmj, I am ok with the groups. It was also interesting to see the groups did not walk, apparently Faxons stress relief process works. All the group were centered in about the same place on the target, just a hare low and left.
I will be going with group 3 going forward, and plan to do some slower fire testing to see how much the heat caused the group sizes to open up.
Before I forget. Data pulled from Hornady 11th.
55g Hornady fmj
CFE 223 27.0g
CCI 450 (small rifle magnum)
once fire Lake City brass.
Col, varied by load, but within the cannelure area on the bullet.
I watched the Hornady podcast about sample sizes being too small. It basically boiled down to the concept that you need to shoot 20 rounds per group to get reliable data. Whether that be zeroing your rifle, doing chronograph testing, or group size testing.
The other interesting thing that was noted was that, while you should shoot 20 rounds, it does not have to be 20 straight. Shoot how you use it. for a hunting gun 3 round. the idea being 1 round to hit the animal, 2nd round in case you had a bad shot, 3rd round in case everything went wrong. so fire 3, let the gun cool, repeat.
Heres the podcast if your interested https://www.youtube.com/watch?v=QwumAGRmz2I
So I loaded up 140rnds. 20rnds, 7 groups. each group had 0.003 variation in seating depth. went out and shot it at 100yds.
Since I'm in an AR platform, I estimated 20 rounds at once would be worst case. About 2 seconds per shot, enough time to get a good steady sight alignment and squeeze the trigger. gave the barrel a 10min cool down between groups.
1 4.09moa (mean radius 1.18moa)
2 3.98moa (mean radius 1.08moa)
3 2.64moa (mean radius 0.78moa)
4 4.04moa (mean radius 0.86moa)
5 3.36moa (mean radius 0.87moa)
6 3.59moa (Mean radius 1.06moa)
7 3.79moa (mean radius 0.93moa)
Considering this was fairly rapid fire, the barrel got quite hot, and the bullets were bulk fmj, I am ok with the groups. It was also interesting to see the groups did not walk, apparently Faxons stress relief process works. All the group were centered in about the same place on the target, just a hare low and left.
I will be going with group 3 going forward, and plan to do some slower fire testing to see how much the heat caused the group sizes to open up.
Before I forget. Data pulled from Hornady 11th.
55g Hornady fmj
CFE 223 27.0g
CCI 450 (small rifle magnum)
once fire Lake City brass.
Col, varied by load, but within the cannelure area on the bullet.
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