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I’ve had my gunsite 308 for about 3 years now and love it. The issue I am having is only in cold weather. When it is below about 20 degrees my first shot is always a flyer, I’m shooting at 100 yards with a rest, the second shot is about 2 inches off and 3 and all following shots are in a 1 inch circle. If I let it sit and cool completely again to 10-20 degrees it does the same thing. Shooting during the summer is not an issue. I would like to use it for deer hunting but I can’t rely on the first shot when it’s cold outside. Any suggestions?
 

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What happens if it is warmer outside with the first and subsequent shots.
 

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Which powder and primer combination are you using? If it doesn't behave this way in the summer, only in cold weather, then you likely have inconsistent ignition. What are the velocities for these first few rounds? Equally, is it only happening in one rifle with this load - if so, have you cleaned the firing pin bore in the bolt body & ensured it's dry and free of lubrication? (Latter being less likely of the two culprits).
 

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This is a very old issue, in fact to combat the situation, many years ago Hodgdon's came up with "extreme rated" powders that ignite and burn very constant from zero deg to 125 deg F. At temperatures above or below the rated range, they still burn much more consistent than non-extreme rated powders.

Initially, it's the ambient air temperature that determines powder temperature but after a gun has been fired a few times, the chamber will heat up and transfer heat to the powder via the brass case. The same can happen if your ammo or gun is exposed to direct sunlight. Non-extreme rated powder will heat up and increase velocity, which in turn changes the bullet's point of impact. Changing velocities cause vertical stringing. Changes in velocities also affect bullet torque, which in turn affects horizontal stringing.

The solution ….. if you reload, use one of Hodgdon's extreme rated powders. If you shoot factory ammo, you are at the mercy of the ammo manufacturer. Here's a link to extreme rated powders …. click on "take the extreme tour" in any of the listed powders then click on "Continue", then finally click on "Foreward" for actual velocity variations due to temperature changes. Extreme Rifle Powders
 
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