shooting on hot days

[georgia hammer]

If shooting on hot days such as we have had the last week or so, will it affect the accuracy of a rifle or have no effect at all?

[Eagle85]

The only thing to affect your accuracy in heat like the past week is the sweat rolling into your eyes. :D

Every time you pull the trigger, you initiate an explosion within your barrel, and send a metalic projectile (forcefully, with lots of friction due to rifling) out the other end. 95-degree air temp is a "walk in the park" by comparison. :) Cold weather is more apt to give you problems, and that is most likely to be mechanical rather than accuracy due to grease/oil thickening up or freezing, causing moving parts (springs, firing pins, etc.) to move really slow, or not at all. Heat and cold will affect YOU more than your rifle.

[trust me]

Heat and cold will also affect the powder and its burning rate. Powder burns faster with more pressure when hot, producing more velocity and a higher point of impact. Sighting in on a hot August day is fine, but when cooler weather sets in, you better go to the range and see where your point of impact is. The difference is minimal in my low pressure handloads, but if you are pushing the high end of performance with big magnums, it can be considerable. There have been some spectacular blowups caused by someone that handloaded some big magnums up to the ragged edge on a cold winter day, and then fired that same ammo the next summer on a 95 degree day. What was safe in December was deadly in July.

If you shoot factory ammo, don't worry about. Just take time to shoot during cool weather and find out if you are affected. In mine, hot weather raises POI about 1/2 inch or less at 100 yards.