chronograph going bad?

I have been using an old school red box Chrony chronograph for about 20-25 years and have been happy with it for what I need, but yesterday I was testing some loads for an up coming trip to Africa and was using my 458 win mag and last summer the loads I settled on was 80 gr of AA2230 Fed 215 primer and 420 gr CEB Raptor bullet. now this load kicks them out at 2424 fps when done last. but now same lot of powder, primers, and bullets I am getting velocity of 2316 108 fps slower. temp yesterday was 18 degrees. I don't mess with the chronograph at these cold temps but we will have very cold and snow very soon and I will not be able to do load work then. any one have any thoughts on why my velocity dropped so much. weird 15 min ago it was very sunny and 19 degrees and now fog has moved in and everything is getting iced over. thank for your thoughts

Going from 18 degrees to Africa, now thats a temp swing!!

and we have not even been getting any real snow yet just some cold temps, yesterday the wind chill was -7 below when I went out to the loading room to load up a few rounds

What was the temperature when you were getting 2424 fps? If it was a lot warmer than 18F, then maybe that's the difference.

It doesn't seem likely that it would be the chronograph.

In Africa it will likely be much warmer than 18 so your load may be back to 2400. But even if the load is 2300 will it really make much difference? Make sure it's hitting in the right place when you arrive, and I think that hunking big bullet will do it's job.

If you load hotter in that cold it may be too hot in Africa. Load functioning is more critical than an extra 100 fps.

fruitnut said:

What was the temperature when you were getting 2424 fps? If it was a lot warmer than 18F, then maybe that's the difference.

It doesn't seem likely that it would be the chronograph.

In Africa it will likely be much warmer than 18 so your load may be back to 2400. But even if the load is 2300 will it really make much difference? Make sure it's hitting in the right place when you arrive, and I think that hunking big bullet will do it's job.

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the load was made up in about 80 degree weather and temp in Africa will be around 70'S. right now it is dead on at 50 yards and we always check our guns before any hunting takes place especially when Cape Buffalo is the animal to hunt

I'd find a new chronograph and see if that flattens out the velocity swings, the new equipment is pretty amazing.

Get 3 friends together and each pitch in 150 bucks and get the new Garmin chrono

It's very possible it was the temps. I dont know about that powder but 2200 is very temp sensitive. At the range you shoot cape buffalo I doubt it will matter much.

Was the battery new, cold weather kills 9 volt batteries!

Rosebud said:

Was the battery new, cold weather kills 9 volt batteries!

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That was my first thought too. The powder is very temp sensitive and the potential for the an older battery suffering in temps well below freezing are both very likely to contribute to the current readings. Check the 9 volt battery output a 18F with a voltmeter. If you are less than 9 volts the Chrony will be off. If you have a full 9 volts, can easily be the temperature affect on the powder.

Chrony either works or it doesn't, they don't start to go bad, they just quit. Usually wiring or one of the receptors.

I know that when mine starts acting nuts its the battery.

cajun said:

It's very possible it was the temps. I dont know about that powder but 2200 is very temp sensitive. At the range you shoot cape buffalo I doubt it will matter much.

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using AA2230 it is not temp sensitive per the powder comp

hydehunter said:

using AA2230 it is not temp sensitive per the powder comp

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Even powder that is rated more temperature stable still reacts to temperature changes, just less so. Alberta goes from 95 to -50. We all use temp stable powder to minimise the velocity swings, as well as Magnum primers in all hunting loads, but velocity does still change. From 80 to 18 is not just 62 degrees swing it is also moving substantially below freezing from semi hot temps. Even temp stable powder will show speed variations between those two temperatures.

I should tell my wife my old chrony is going bad so I can get a new Garmin. never thought about that before. Hope you have a great hunt. Good luck

Byrdman13 said:

I should tell my wife my old chrony is going bad so I can get a new Garmin. never thought about that before. Hope you have a great hunt. Good luck

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This past year, on several rifle builds, testing out the rifle and then setting up loads, I could not use my old sky screen chronograph, the sun had set below the tree line enough to cast shadows. I was thinking, hell time to upgrade. A month later the wife asked, what do you want for Christmas, she opened up the price we usually spend when she decided to upgrade her wedding band at 1500.00.... I said well, I have been wanting this Garmin chronograph, right off the bat, what is wrong with the one you have... I explained the situation and she was like okay, how much... I said here it is, she swallowed her tongue and asked, you think I am made out of money . I asked let me see that left hand and that ring finger, what am I paying on the "upgraded band"??? Luckily, with my business account at Brownells, I did not pay the price advertised and got it home for about 30.00 less than listed price. However, she made darn sure it was wrapped the second it came in, so will not get my hands on it until tomorrow