Two chronos and a ballistics program.

I have a MagnetoSpeed chrono that attaches directly to the rifle barrel. So it is measuring velocity beginning ~3" from the barrel.

The start sensor for my CED M2 is 10' from the muzzle.

When used together on the same shots, the two measurements correlate well. But the difference between them is greater than expected velocity drop over 9' 9". So, they are giving slightly different results.

My conclusions are that the MagnetoSpeed reads a bit high and that both are accurate and useful for the intended purpose, certainly as accurate as our powder scales are lol.