Search:

No you lose approximately 30 msec doing that.
To stay within sane pressures, I think it would be difficult to bring a 260 up to 830 msec in a 20".

No you lose 30 msec doing that.

Short barreled 6,5x284 out to 1150 meters, 20" and not 18,5" as Gimp said.

http://www.youtube.com/watch?v=IzzouI0BBrA

You'll get:
A compact rifle that let's you react fast enough to make use...

Shooting Chrony is not bad, it's just that they are light dependant and reading will vary with the light.

My guess. Can't argue with physics, the math is well known, bullet is well documented, the weather isn't a big enough factor so that leaves the measurement?