chronographing

[JonnyBender]

At what distance should a chronographe be set up from the muzzle of the rifle?



JonnyBender

 

[TRECustom]

Jonny, the maker of the chronograph will have a recommendation. I set up with the first screen at approximately 7 yards. The boomers,.338 x .378, .460, etc.) will give false readings if I set up closer, and the window you shoot through gets too small if you set up much farther. Even at 20-21', the shock wave can still rock the screens, but I don't get error readings. There is a formula for converting the instrumental velocity to muzzle velocity, but I just use the instrumental for calculating exterior ballistics. Works out for me.

Good shooting, Tom

 

[Silverfox]

I don't have a big loudenboomer caliber, but I always try to get the first screen set 12 feet from the end of the muzzle on my rifle. That's also about as far as I can get because of the length of the cable. I have a Beta Master Chrony and I've never had a problem with too small a window, but I do take great pains to make sure my chronograph is set up in near-perfect alignment with my target and that I'm shooting the bullets the right height over the screens as per manufacturer's directions.

Like the previous poster mentioned there are fomulas and software available for converting the muzzle velocity from the speed your chronograph reports. I can't remember the URL, but part of the name of the online software I use for my trajectory charts and finding my muzzle velocity is 'JBM Trajectory'.