I tried it at 10 feet and 10 yards when I moved to 20 yards I got less variation from shot to shot and a whole point better on standard deviation. I guess every one has to do what works with the equipment they have.

Thanks for all the replies. I was surmising that the sabot would play havoc with a reading. But I'm glad I asked the question because I never thought it would destroy a chronograph too! Once the weather gets nicer and I get over this darn flu I'll have to go try it. Will post results for your info.

Does the company that make your chrono offer a shield.

Something like this

http://www.competitionelectronics.co...debris-shield/

Not sure...I 'll have to check it out. I have an inexpensive Chrony
I'll probably end up just using a piece of 1/4" plywood i have lying around and brace it up in front.

Even if it is inexpensive - it is not fun to break one!