Shooting Chrony Problem

[gunslinger20]

I have a shooting chrony master that I sent bacl to the factory the end of last year for erratic readings, got it back this winter and guess what!!!!!!!!!!! the same thing. Load 310 gr. lee g/c boolit 45 colt 7 1/2" bbl 19gns 2400 WW cases WW lp prim. Readings from chrony I dont believe any of them overcast day 70 degres with sky screens 1538 fps 1538 1541 1533 1059 1078 Alloy bhn 14.3 2 1/2" GP 25 YDS NFG. also shot 18gns 17 gns.

What are your expierances with shooting chrony and what chronagraphs are you guys useing?

[Bill]

I use the same chrony. The range in numbers might be caused by loading methods. Different cases, difference in bullet seating and crimp. Variance in powder measure, a tenth of a grain will change velocity. billet size also has an influence I shoot 1911 45acp 230 lrn and vel. changes from gun to gun and brass differences

[Maven]

gs20, I have the F-1 Shooting Chrony, but don't have a problem with erratic readings or erratic readings when the sky's cloudy. Rather, it doesn't read at all with skyscreens or without when the sun's is overhead. The cure for that is to either shoot earlier or later in the day or to angle the tripod head away from the sun, which also makes for an oddly angled opening. Inconsistent readings may sometimes occur because the chrono. is too close to the muzzle and/or because of the propellant used. The very slow milsurp IMR 5010 is one powder that will do this. Try moving the chrono. farther away from your gun, say at least 12 ft. and possibly even 15.

[BD]

My simple test for this is to shoot a long string of Eley match .22s and look at those velocities. I don't see anything in your load that would make me suspect erratic velocity unless the boolits are jumping the crimp. Are the lower vels always the last couple rounds?
BD

[wellfedirishman]

I just got the same model recently and found it to give accurate readings consistently. I shoot a few 22s through it at the start of a session to confirm it is reading correctly.

If it is too close to the muzzle you will definitely get funny readings. Move it further out.

And one last tip: Put a piece of duck tape across the top of the skyscreens to hold them together, just in case you shoot a little bit high and nudge the screen. Ahem, don't ask how I know...

For the money, it is a very nice product.

[Hip's Ax]

I was told to bring my sun cover (IE: EZ Up, or my cheap K Mart "tent without walls") and set it over the chrony. Apparently this solves all sun angle problems. Have not tried it yet.

[Artful]

Silly question but what distance from the chrony are you shooting - I had a bud with problems with his 40 XD and then he shot his - so I went out with him and he want to shoot offhand over my chrony from about 5-6 feet away mine gave erratic readings also but I made him back up and we got better readings until he grazed my chrony and I made him stop.

[gunslinger20]

I had an old f-1 for years, always worked greate untill it finally gave up the ghost. This unit has the remote with a 20 ft. cord so it was about 20 ft from the muzzle. Some successive shot strings had errors or droped the entire string. I even reset the unit to factory specs (removed all working data) Boolits werent pulling on recoil. The first readings in the 15s seems high for this load. 19gns 2400 I think should be a good load for this boolit. It was around 3 pm when the shooting session started. Irishman if I put duct tape on top of the sky screen the boolit wont have a light background to cast a shadow on the sensers will it?

[Cranium]

I have a Pro Chrono Digital with the USB interface.

It has been rock solid up until last Sunday when I had some rounds indicating they were traveling at around 500 fps when the expectation was closer to 1100 fps. Not sure if the position of the sun was causing this but it cleared itself up and I have 350 rounds downloaded and logged in a spreadsheet for reference now.

[Mk42gunner]

I've got one fo the old Chony's that came with pressed paper aiming guides, worked great until my buddy shot a .257 Wby through the guides at about six feet. the muzzle blast blew them apart. (Last time I let him shoot through it, too.)

Anyway, how fresh are your batteries? Mine will give erratic readings if the battery isn't up to snuff. I usually buy a new battery for those just in case moments.

Robert

[gunslinger20]

Battery was new. My old one also has paper guides.

[firefly1957]

I also have one of the old units it needs alkaline battery to work right a "heavy duty 9 volt battery will not give good results. Another problem I have is muzzle flash can give bad readings My 10" contender in 30-30 is a real pain to get readings as it has a lot of muzzle flash. That problem goes away if I move Chrony over 30 feet from muzzle.