I recently bought a CED M2
from Len here on LRH. After using it a couple times I was really pleased but then ran into an issue yesterday that has me stumped. Not sure if the chronograph has anything to do with it or not.
I just got my new 338 Edge from Shawn complete with test target and his recipe for 300 SMKs (90 grains H1000). Shawn had graphed this load at 2812 out of my rifle. The first test session yielded an average velocity of 2775 with an ES of 9! I held back 5 rounds from that loading session for future use.
Shawn suggested I bump the powder charge up in .5 grain increments to try to get up around 2800-2830 fps. I loaded 5 at 90.5 and 5 at 91.0 and headed out to the range this weekend.
The weather and lighting conditions were nearly identical to my previous session, I was even at the same bench. The chrongraph was set-up 18 feet from the muzzle (like before). I use a laser bore sighter to make sure the barrel and graph are set-up perfectly aligned and centered 4" over both sending units. It was sunny with a light haze of normal Illinois humidity. I had the sun screens installed.
The rounds loaded at 90.5 grains averaged 2635 fps ES of 10 and the 91.0 grain loads averaged 2652 with an ES of 12! During this process I backed up and also shot the 5 rounds from the previous lot (90.0 grains) and they averaged only 2613 with an ES 7!
Suggestions? I feel very good about the repeatability of my set-up. Am I missing something? I have an email into the "top technical guy" at CED but thought I'd also run it by you guys.
Thanks in advance.......