Stupid little things that effect ELR

[Shawn Carlock]

While out testing the new LRKM in 338 Edge +P the other day I ran into an issue I know about but had spaced off. I had validated my ballistics out to 1360 yards with this rifle and set the speed in my program. A friend and I went spring bear hunting just the other day and spotted a coyote first thing at 1162 yards. I was in the back of my mind already thinking how cool the video was going to look when I X- Ring this coyote. I dialed up the programs elevation, we talked about and dialed in the wind, I took the shot at a still coyote with a broadside presentation and promptly shot perfect windage but over its back. My buddy called 1 moa high, the coyote of course took off and ran quite a distance out to 1400+ where we got a range on him and repeated the dialing process etc. When I broke that shot it too was 1 moa high. I stared at my newest creation with that blank "What in the Hell" look, it just didn't make any sense.
Long story short I had been shooting a lot of 200 rounds of virgin brass that chronographed at 3102 fps and that is what I had validated for. The load I had grabbed and used were 2nd fired cases and chronographed 3138 fps. Of course if you run that number into your program it is clear why the video shows my less than stellar performance.
My point in this thread is that when you start into the 4 digit range (1000 yards +) no matter how small everything make some difference. The 40 fps difference in my 2 loads was responsible for about 1moa in elevation causing me to miss what would have been a "Kodak moment". The same can be said for many other minor issues that would not affect the 3 digit shooter, I have listed a few of my favorites:

If your ES is 25-30 fps instead of single digits.

Using temperature sensitive powder (even if it is only 50 fps from 30-100 degrees).

Failure to look at the anti cant bubble.

Failure to add in the 5 degrees the angle of the shot changed as the target moved.

The tree limb that is at mid range and 50 feet above your line of sight that you hit because you didn't think about the height of the ark of the bullet.

But my favorite ELR issue is relative group size, when you shooting a group that would barely fit on a 5 gallon bucket and are getting bummed about it, you then realize that your shooting at 2543 yards and holding well under minute of angle.

So to sum this thread up, the issues that don't even concern the 3 digit shooter can make or break the 4 digit shooter so pay attention, dot the "I's" and cross the "T's" because that is what ELR is all about.

 

[Broz]

Good post Shawn. At 1400 yards if you take the hair off that yote he is about 1/2 MOA in height at his thickest point. When I hold 1/2 MOA accuracy at this distance I get a big smile on my face. 4 diget yotes are tough.

Jeff

 

[paphil]

I could not agree more! I have a chart printed up that runs out to 2000 yards for my 7mm. We preach and teach all the time about there being little difference at 500 yards and 1/2 click at 750 (1.25 inches) and 1 click at 1000 (3.75 inches) for each 1000 feet or 20 degrees temperature change. (1/3 moa clicks, VLD bullet) We don't even worry about the barometric pressure! Now when we go to 1500 yards, that 20 degrees/1000 feet now becomes almost 19 inches and at 2000 yards we jump to 61 inches! so at 2000 yards only 1 degree temperature change causes about 3 inches up or down POI! Each 100 feet of elevation causes about 6 inches of vertical POI change. One half point barometric pressure change 29.5 to 30 will move POI about 30 inches vertically! Add in spin drift and earth rotation and it seems nearly impossible to hit anything at 2000 yards. The larger calibers and higher bc bullets will help some but all these things still have an effect as well as the powder and components! I'll stick to teaching 1000 and less where there is lots more room for error!

 

[grit]

What stands out to me is, you figured out the issue. ELR is thrilling! Sometimes the accuracy of these rigs is just awesome. Other times, we have our W.T.H. moments. Taking notes, figurin' it out, and continually perfecting our system is what gets it done. This one got away. If the next one does, it likely won't be for the same reason!

I once got to take several shots at a couple of coyotes in the 1300 yard range. About round three, I took fur off of one. I was let down when all I found was hair and a sprinkle of blood, until I put my shooting into context. Not a shot missed point of aim by more then 3/4 minute!