Chronograph help

[drenner43]

So I just recently shot my first handloads. I had the chronograph about 15 feet away. There was a little bit of wind. I was shooting an unbraked 220 Swift, a braked 300 win mag, and a braked 30-378 Wby Mag. I got very inconsistent readings between loadings on all 3 guns. It was my first set of reloadings but I paid close attention to brass length, COAL, charge. Anybody have any ideas what my problem could be?

Also, what is everyones suggestion on chrono setup for shooting.

I dont have the numbers from the loads, I misplaced my sheet. It wasn't like 400 fps difference but was as much as 100 fps or so I believe.

 

[bbutturff]

What was the air temp and how long was it between shots? On a warm day my 300WSM can have an ES of over 100 fps if I don't let it cool down. Yesterday (50 deg.) I could keep the ES between 10 and 15 fps and only had to wait a few minutes between 3-shot strings.

 

[drenner43]

I was shotting 3-4 shot groups with a very short time between firings, maybe 2-4 minutes. I never let any of the barrels get hot, only slightly warm (all loads were very mild starting loads). I dont remember the temperature exactly, i'm thinking somewhere between 60-75 max.

 

[CRNA]

I have found that my chrono reads the best when the sky is overcast. If there are clouds passing by giving varying levels of light, or if the sun is at an angle shining on the chrono I get really bad numbers. I shot a few rounds once with my 7RM on a partly sunny day with partial and inconsistent cloud cover and I had readings from 3000fps all the way to 1112fps!!!! If possible I try using the chrono late in the evening or on completely overcast days to get the best performance out of the chrono.

 

[newmexkid]

My first chronograph was , (and is) a Chrony. The 1st one went haywire right away. Cabela's replaced it and then I read clear through all the instructions before using the 2nd one. The instructions say to place the unit about 10' from the rifle barrel. I was placing it 15'-17'. Secondly, my aimpoint through the V-rods was almost at the top of the "V". Again the instructions say the sweet spot is about 4"-6" above the unit. Well, today I went out with the new unit for the first time and...Bingo!! My velocities printed out right where I thought they should be. Guess it pays to read the instructions. Not saying you didn't. Just relaying what happened to me.

 

[drenner43]

thanks for the help guys