Friend and I placed our cronos in series as close as we could get them and put 10 rounds of his .40 handloads thru them. That meant the same bullet went thru 2 cronos.
His crono was first, mine second. Mine read 9fps lower than his. Which we figured is pretty much good enough.
Didn't do the experiment of reversing them because we were just seeing that they were pretty close to each other in readings.
(not sure what models they are - not even too sure what mine is without looking)