PROJECT Black Spider (Phase 2)
Some of the groupings compared with a dime.
DAY 1: Testing different charge weights.
Bullet: Hornady 73-grain ELD-M
Casing: Lake City Unprimed, Never fired
Primer: Federal AR Match
Powder: IMR 8208 XBR
Barrel: SRS Match Barrel, 18” 1-8RH Twist, Intermediate Gas-Length, .750, SS, 5R
Please read part 1 in order to get the full picture of this project. It is titled “PROJECT Black Spider”.
I was excited to test the charge weights that I reloaded last night. I went ahead and pumped out 24 rounds, 4 different loads, and 6 rounds per load. Like I mentioned on the last blog, I started halfway up the minimum and maximum load spectrum in order to weed out the slower charges.
So the day turned out great for shooting. The temperature was about 70 degrees and the wind was blowing from left to right at about 0-3 mph. I decided to go to a local range near Ft. Carson, Colorado.
Once I was in my lane and set my target up at 100 yards, I started to prepare my area to shoot in the prone position. I turned my Kestrel on ahead of time to start tracking the “environmentals”. The next critical step was to keep my rounds out of the sun and setting up my Magneto Speed chronometer. Unfortunately, I wasn’t able to set the chronometer correctly due to the handguard being too near to the muzzle. The support pads on the chronometer couldn’t get its surface on the barrel at 100% contact. It had about 90% barrel contact and 10% muzzle compensator contact. After trying to fix the problem for about 8 minutes, I decided to move on without clocking the FPS. I will clock the FPS another day.
So the plan was to shoot a few foulers just to foul the barrel a bit before getting started with the test. This would also help me ensure that I am at least hitting paper. I loaded 15 extra rounds somewhere in the middle of my four different charge weights. I charged the 15 rounds at 22.2 grains. The conditions were set. I used no shooting mat, just me laying in the prone on the cool concrete. I was thinking about using a sandbag in front of the bipod in order to load the bipod a little better, or affixing it to the wood post that was lying vertically in front of me. But I thought, if I zero, or test in this manner, then I will need to have this same advantage every time thereafter. One thing they preached in Sniper school was consistency equals accuracy. Do everything the same every time. I didn’t want to spoil myself by adding such an advantage that I wasn’t guaranteed to have in future engagements. So I decided to shoot with just the bipod and a shooting bag.
The magazine is loaded with the first 3 rounds to foul the barrel. I’m in the prone taking note of the readings on my Kestrel and send the first 3 rounds down range. I felt the pull on the 1st and 3rd shot. I put the weapon on safe and dropped the magazine before looking through my spotting scope. As I was confirming the shots, I noticed how wide the grouping was. My CALL was 1” to the 11 o’clock, center, and .5” to the 6 o’clock. So I knew that shot number 2 was the original placement. I sent the next three rounds down range, and boy let me tell yah, all 3 shots felt great. My CALL was center, center, and center. Long and behold, 2 of 3 shots were touching, and the third wasn’t far from the first 2. How’s that for adding some fouling to the barrel? LOL. The grouping went from a 2.1 MOA to a 0.5 MOA with only 6 shots. I started to think that 22.2 grains might be the optimal charge. For some reason I was thinking that the 73-grain ELD’s were going to be too good to be true in my barrel. But boy was I wrong. But I didn’t want to celebrate too early. There was more work to be done before counting my chickens. I had 9 more rounds of these “fouling” rounds, but I was confident enough to move on to load 1 (21.6 grains).
As I started to load the first 3 rounds of “load 1” into the magazine, I noticed that the first round felt a bit warmer than the others, so I took note of this in my notebook just incase I would notice any ill effect in its ballistics. After sending all 3 shots downrange, I noticed no ill effect in the warmer round. In Sniper school, the instructors would ream us a new one if we didn’t keep our rounds cool. We would cover them with our hats, a sheet of paper, or anything we had around us in order to block the sun from hitting these rounds. Not sure if it’s a myth, but I was always trained to keep the rounds out of the sun. So as for load 1, it looked pretty promising, except for the fact that I pulled one. My CALL was center, .5” to the 6 o’clock, and center. This grouping came in at .8 MOA with the pulled shot. The extra noted that I jotted down for this string was, “Didn’t feel confident on this string.” Take that for whatever that is worth. Alright, moving on!
I decided to shoot a second string of load 1 again. I noticed that the grouping opened up significantly, so I knew that this must have been human error. Here’s what I took note of, “changed the bipod setting to 1 notch lower, tighter pull of the rifle towards the shoulder, and readjusted the parallax”. That is definitely enough factors to change the grouping significantly. This group came in at 1.4 MOA. For this load, I just paid attention to the first group of load 1 and moved on to load 2. My CALL’s on load 2 were, 1” to the 4 o’clock, center, and center. My noted were, “relaxed on pulling the rifle to tight into the shoulder, and held a firm grip only right before taking the shot”. As you can see, this grouping came in nicely at 0.4 MOA. Except for the fact that the pulled shot actually went to the 9 o’clock. Calling the shot isn’t easy. This is something that you have to practice over and over before mastering it. You get to learn your shooting habits and your rifle well enough, that you will be able to CALL your shots accurately at least 95% of the time.
Load 3 came in at 1.1 MOA with shot number 2 going through the same hole as shot number 1. I accidentally misidentified this grouping as 22.0 grains, when I fact it was 22.4 grains. So far, it is looking like somewhere between 22.0-22.4 is the sweet spot. In my notes it says that I felt a bit hesitated on the second shot, and rushed the third shot. I also noted that the lane to my left was occupied by someone shooting a damn musket, which was covering my LOS (line of sight) with the blast of smoke from the black powder. They had literally just gotten there shortly before shooting this string. Another note I jotted down was the fact that I had to change the target. So I took a break until the range cadre called a cease-fire.
Next up was the second string of load 3. I wanted to get a better judgment of this charge before moving on. This second string came in at 1.4 MOA. The grouping would’ve been horrible even if I didn’t pull the third shot. The most important note that I took during this string was, the sun was in my eyes. I still had a clear view of the target, however. The next load was load 4. I shot both strings of load 4 and they averaged at about 1.4 MOA. After seeing the groups open up like that at the maximum charge weight, I decided to go back to the second string that I had left on load 2 and shoot another group.
This grouping came in at 0.9 MOA and I was a bit quick with this iteration. At this point, I had two more targets downrange, so I decided to shoot two 3-round groups at each of the targets. One came in at 0.7 MOA and the other came in at 0.5 MOA. I was very satisfied with the results.
In closing, I was a bit worried that the 73-grain ELD’s weren’t going to like my barrel. Most of this lack of confidence was because of forums that I had read on the Internet. Some people weren’t having any luck in barrels that had the same twist rate, so I thought I was just going to be like the others. But I’m glad that I had better luck! The next phase of this project will be gathering data at various distances, and using a chronometer to measure the FPS.
Thank you for following this blog. I promise you this is going to be well worth it, especially for you guys that are running a DMR platform in the same caliber. Until next time, Happy Thanksgiving and have a wonderful weekend.
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– Cain, Owner
Superior Rifle Systems, LLC
“Long-range is my journey.”