Mornin Gents, I bought a new CED chrono and have just started using it. I read in an article by Barsness that he puts translucent tape over the ports/windows to keep dust from fouling/clogging them over time. Any thoughts on this?
Also, how does one go a/b "correcting" for actual mv?

Thanks

As far as putting translucent tape on the chronograph, I've never tried that. But the easiest way to figure correction for muzzle velocity is to use a ballistics program, like JBM.
http://www.eskimo.com/~jbm/cgi...jbmtraj_simp-5.0.cgi

Input your muzzle velocity about 10fps faster than your actual chronograph reading at 12', set the range increment on the JBM program at 4 yards, and look at the difference between the muzzle velocity you input into the program, and the velocity showing at 4 yards. You can tweak the muzzle velocity you input until the 4 yard velocity reading matches your chronograph reading at 4 yards, and you will have a good idea how much to correct. Knowing your actual muzzle velocity will help the various ballistics programs and drop charts work more accurately for you. Keep in mind that the BC you input may only be fairly close to actual BC, since many bullet makers estimate these BCs based on calculations, rather than actually measuring them. Also, BC varies with velocity. You can play around with variations in BC (+/-.030) to see what difference it makes.

I don't know how the translucent tape would work. It'd be easy enough to check. I've had a Chrony every since they first came out. Same one. And anytime I'm not using mine, I put plain old masking tape over the light holes to keep out dust and crud and remove the battery. It's still going strong.