I have a little red "Chrony" chronograph that I used when I had an archery shop a few years ago. I'm new to reloading so I thought I'd use it (rated up to 4500 fps) in place of buying a more expensive one.

I've shot two rifles across it. I get velocity spreads up to 200 fps per load. Is my loading that bad or my chrony is a liar? The conditions were good with no errors reported. However, I measure each charge...just don't think it is me. Anyone have similar experiences with cheaper chronies?

actually it is not unusual to find loads 200 and more apart. Shoot a few more and take an average. many moons ago a couple of us decided to see what kind of differences there were between ball and stick powder and between weighing and measuring them. what we found out was that measure ball gave the most consistent readings, followed by measured stick then weighed ball and then weighed stick. the weighed stick frequently gave 2-300 FPS differences.

Hmm...didn't know that. How in the heck can rounds with that much variance have even close to the same impact? Looks like that would spread them all over the place...

Are the screens for archery which measure velocities near the 300 fps the same screens for high velocity centerfire? Your chrony is rated for the high stuff but is are your screens?

A simple way to check a chrono's reliabilty and/or consistancy is to fire some 22 match grade ammo across it. High grade 22 match ammo doesn't vary much in velocity from round to round.

quote:

Originally posted by Born to Hunt:
I have a little red "Chrony" Anyone have similar experiences with cheaper chronies?

Yes!!!!!!!!! I'm a slow learner. After my third Chrony I got an Oehler.Some of the change was due to the lack luster Chrony approach to helping there customers solve problems and my inability to understand English as spoken in INDIA. The Oehler people in Texas go out of their way to make things right.It is just a little easier for me to understand Texas English if spoken slowly. roger

The earlier chrony models were quite light sensitive.However I don't find that problem with the newer models.My shot to shot variations are usually in the 20fps to 30fps range.

Sometimes muzzle blast will cause errors.
Back off another 10 feet and look for a change.
Good Luck!

quote:

Originally posted by hawkins:
Sometimes muzzle blast will cause errors.
Back off another 10 feet and look for a change.
Good Luck!

Hawkins is right . One of the problems I had was the unit was affected by GUN SMOKE. The readout connecting cable was too short and they could not supply a longer one.After searching for some time I gave it up. I'm quite sure the GUN SMOKE thing was real because when I was using rifles with recoil compensators I got good readings. roger

Thanks guys. I do not know if my screens are rated for rifle velocities.

I think a new Chrony is in order or at least maybe I can find someone who owns a nicer one and fire some identical loads and see what the readings are.

I was set up 10 feet behind the Chrony.

I went through three Chrony's like yours before I got rid of them. They are susceptible to light conditions and can show a variance that isn't true. I saw even more variance with identical loads which in one case scared me to death. I was at max on a load at 2850fps and the next day the same load showed almost 3200fps!!

One of the "fixes" that was around for quite a while was to put some translucent Scotch tape over the sensors. Many swore by this fix and their accuracy returned. Before you buy another chronograph try this, it may work.