A question for the more informed than I, please. I wish to calculate what my .243 CZ 550 is putting out as I have recently read an article by Bruce Potts of shooting times (2nd Jan2013 edition) which warns of the depleted speed and energy when barrels are shortened. My CZ has a barrel of 20.5 ins measured from the start of the chamber to the crown and an ASE Utra S5 muzzle mounted moderator. I have always been pleased with the results I get, which are almost always reasonably sized fallow bucks in the Essex area, and am not really considering changing rifles because of one article. However, a seed of doubt has been sown and as a result I have borrowed a chronograph from a pal to check out the speed and energy to reassure myself. Whilst it tells you how to operate the chrono it doesn't give the formula to calculate energy from muzzle speed. Any help and opinions would be appreciated.