Temperature and Shotgun Range
Many times you will see a 20 or 30 degree temperature fluctuation on a typical turkey hunting day. You might have a 55-yard gun in the late afternoon, but that same shotgun may max out at 50 yards on a cold morning at daylight.
A 20 degree drop in air temperature is going to lower your pellet count enough to cost you maybe 5 yards of range. So you have a couple of choices. The easiest thing to do is pattern your shotgun and establish your max range at the coldest temperature you plan to hunt. That way you just have one distance to worry about, unless you get some unusual weather.
But if you want to take advantage of every yard, you will need to shoot your shotgun at various temperatures to establish a connection between temperature and range. Here is an example of what you might see below.
Humidity and temperature will also affect patterns, but those effects are negligible under field conditions. Even if you clean your barrel between shots, you still might see a 10 or 20% variation from shot to shot. For this reason, it is best to base your decisions on a 3-shot average.
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