chronograph going bad?

[hydehunter]

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

 

[Seabeeken]

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

 

[hydehunter]

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

 

[fruitnut]

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.

 

[hydehunter]

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.

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

 

[waveslayer]

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

 

[cajun]

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.