One of those shots were about 35 fps difference though. Never did figure that out.
35 fps is well within the extreme spread of most ammunition. So, which one was right? My experience with the LabRadar shows attention must be paid to alignment, before and during shooting. Mine gives good readings as long as I do that. It is not uncommon, however, for it to get bumped and numbers go crazy. This happened during a recent class when the students were measuring velocity with both an Oehler and the LabRadar. Numbers were in good agreement for the first couple of students. By the 8th student, it was obvious the ball head on the mounting plate wasn't tight enough as the machine had drooped. My fault, not the LabRadar's fault.
Another incident was when informally shooting some shots ammunition and a new rifle last August. It was a quick look and I used the LabRadar by itself instead of also setting up an Oehler. Expected velocity was in the 2680 fps range. Measurements were going as expected. Suddenly, I got a velocity of 7,400 fps. I saw the bullet impact the berm so knew it didn't go high. I navigated the LabRadar to the page that showed all measurements of that shot and it gave:
V0 - 7400
V3 - 6977
V25 - 2666
V50 - 2631
V75 - 2597
V95 - 2572
So, it appears, the numbers at 25 yards and beyond were likely correct. Either that or the bullet "slammed on the brakes" between 3 and 25 yards. Such a large error is easy to see. What if it had been 45 fps? I wouldn't have reason to suspect one reading that is 45 fps off. It wasn't important so I really don't care. I discarded that shot and went on about my business.
I also have to monitor students to ensure they line up properly on the skyscreens when using the Oehler. The "proof" value will tell me when they get misaligned.
All chronographs can give a bad reading. Dr. Oehler recognized that a long time ago. It is the beauty of the "proof" screen. If something is wrong, it will tell you. You can then diagnose and fix the problem. Having the "proof" measurement has saved my bacon...more than once.
Although the Oehler includes the "proof" screen, the same benefit can be realized if you use two chronographs for all measurements. Well done, Casey, on your comparisons.
There is no doubt that people trust the Oehler equipment. It has long been the "gold standard". Have you ever seen anyone claim to trust an Oehler because they "Checked it against Brand X"?
