Two weeks ago I had the pleaure of shooting my chronograph- twice. A shooting friend gave me one of NAA's micro .22LR revolvers to pull down some velocity figures. Having never fired one of those micro-guns, I didn't know that such a short sight radius means big variations on point-of-impact. I loaded four rounds (I don't know why four)- Lapua 22LR standard target rounds. The first round- 560fps. Second round- no reading. Third round- 227fps. Fourth round-544fps. After the third round I noticed that the chrony wobbled a bit- and the 227fps reading was bizarre.
Long story short, rounds two and three hit the protective plate that guards the first light meter on the chrony- giving the plate two significant dents. The third round (or a piece of it) somehow came off the plate at such an angle as to actually proceed over both light meters- giving the 227fps reading. On the way through it bent one of the front skyscreen posts a bit.
The chronograph now works flawlessly. It's the same Shooting Chrony Beta that I'd complained about earlier. I'm assuming this is how many of us adjust our chronographs- the question is, what's your favorite gun and load to shoot your chronograph with?