F1 chronograph

[rgcda]

How accurate are these chronographs. I just bought one and tested out a couple of loads for my 270 WSM.
70gr of Reloader 19, Rem 91/2 primer, winchester brass, 130gr Hornady bullet, 24 inch barrel in my Sako A7 rifle.
registering velocities of 3759, 3768, 3761 fps = seem way too fast.
sunny day, about 90 degrees and I was following directions included
unit was about 12 ft away from muzzle.

 

[JDGray]

Sure you weren't shooting 90gr bullets? That does look too fast for the 130s.....Try again at 15ft or more

 

[Galil5.56]

I had one (F1 Master) that was fast, which was only one of it's many issues that made me very glad I no longer use it. Comparing it to a circa 1993 F1 and nearly new ProChrono Digital, showed my particular F1 Master one to be about 5-6% fast from the others. User error, sensor cleanliness, low voltage batteries/improper batteries, improper setup, whatever, was not the issue. This same chronograph would also record very slow at times too.

Have read of other similar results over the years of reading web forums, so it seems I/we are not alone. Guess any brand could have the same issue, but I can recall only the Shooting Chrony brand being named. Some examples:

http://www.6mmbr.com/ballistics.html

Post #2:

http://www.longrangehunting.com/forums/f19/shooting-chrony-3478/#post25303

John Taffin tested 5 different chronographs, and his Shooting Chrony overall had the highest avg velocity all but once, and always the highest recorded result per string, but only by a small amount, not like I and some others discovered.

 

[gamestalker]

You have to be careful at how far or close you are to those because they can be effected by sound waves emmited from the muzzle. I like to shoot at about 20' away so eliminate any factor that could cause problems. I'm thinking your's was reading something else becaue you might have been to close. I have the F-1 and think it's a decent chrony. I once had .357 mag. loads that were producing 2900 fps and all other really not possible fps. So I backed up to about 20' and then I got consistent readings that were realistic. Don't be concerned about the effect of 20' or 30' on your readings, it isn't far enough away to make a big difference, but it is far enough awaytoget realistic readings.

 

[rgcda]

thanks all. I will try moving back to 20ft. and see if there is a difference.

 

[[email protected]]

+1 on moving a little further back. I was working up some 9mm loads with my F1 and i managed to push a 115gr 9mm bullet at over 7000fps.

 

[GP100man]

& make sure it`s unfolded all the way & as flat as possible , +another on 20`min.