Author Topic: Temperature (Read 820 times)

Leftoverdj · « **on:** May 29, 2004, 01:49:36 PM »

I own a finely accurate CZ-452. That is, it has always been accurate with a couple of brands of match ammo. I have bought a wide assortment of less expensive ammo and have always been disappointed.

Today, I pulled out the CZ and started to burn up some Federal Target that I had paid about $2.25 a box for. In previous tests, it had shot about 1" groups at 50 yards. Today it was doing about half that with a best group of .506 edge to edge which I make to be .284" center to center.

Only thing that has changed is the weather. It was in the mid 70s today. My previous shooting with that ammo was in the 40s or colder. I'm wondering if the temperature really made that much change and whether the change was in the powder burning or the lube consistency.

Anyone else had this experience?

ironglow · « **Reply #1 on:** May 30, 2004, 06:54:54 AM »

DJ;
I can't answer you directly, but the folks over at

<www.pmcammo.com>

probably can.They have a forum over there that is moderated by one of their engineers who is ready to do his best at answering ammo questions..

BTW...that's some "good shootin" , LeftoverDJ!!

AZ223 · « **Reply #2 on:** June 06, 2004, 11:15:17 AM »

I've had the opposite problem here in AZ with my .223 Ultra. In January, I sighted it in to shoot under 1" groups at 100yds, and 1.5" at 200; that was around 60-70 degrees. Now I take it out in 105-110 degree heat (sitting in the shade, thank God!) and my groups went to 2"+ at 100 and totally embarrassing at 200. Also, they went an inch higher at 100yds at the warmer temperatures. I don't know what other factors my be at play, but I adjusted my scope down to where I want it and it's a little better.

Last weekend I was out plinking in the hot sun, and was picking off things as small as potatoes and pressurized cans at 100yds. As I think about it, the scope may be the culprit -- it's a Bushnell Trophy 3-9x40. I'll have to see what happens when the weather "cools down" to the low 90's again -- maybe in 5-6 months.

ScatterGunner · « **Reply #3 on:** June 11, 2004, 01:53:56 PM »

temperature has a direct effect on your ammo !

in general, for a given load, the hotter the temperature is it when you shoot, the higher the pressure will be in your cartridge when it is fired.

this can have be good or bad depending on your rifle ! tune your ammo for the temperature that you intend to shoot it at, simply put don't use your winter reloads for summertime shooting !

sg