Weather effects on patterning

[PAbigbear]

Just curious how much effect you guys think the weather has when patterning?  I just polished my 870 20ga and my 835 yesterday and wanted to hit the range today, but its cool (40deg) damp  and dreary with light winds.  Supposed to be in the mid 50's tomorrow with sun.  I'm going to wait til tomorrow anyhow.

[mightyjoeyoung]

There is no think about it.  It is a fact that weather will affect shotgun patterns.  Warm dense air holds the pellets "together" longer while cooler, air will allow the pattern to spread out faster.  Here's the thing though...I pattern for best pattern of course, but then I also pattern for HUNTING CONDITIONS.  The best pattern you get on a hot, sunny day won't be there when it's 36 degrees and drizzling as you slowly squeaze the trigger on that monster gobbler strutting at 40 yards...

[mcgruff1533]

There is no think about it.  It is a fact that weather will affect shotgun patterns.  Warm dense air holds the pellets "together" longer while cooler, air will allow the pattern to spread out faster.  Here's the thing though...I pattern for best pattern of course, but then I also pattern for HUNTING CONDITIONS.  The best pattern you get on a hot, sunny day won't be there when it's 36 degrees and drizzling as you slowly squeaze the trigger on that monster gobbler strutting at 40 yards...

You have the right idea, but your facts are backwards.   Cold air is more dense than warm air.   This is why engines make more power when its cold out.   More oxygen is ingested per combustion cycle because the air is more dense.   Cold temps also effect powder burn rates, and certain powders can lose a fair amount of velocity in the cold.   Of course, I'm talking about extreme cold which we are not likely to be turkey hunting in anyhow.

[allaboutshooting]

Just curious how much effect you guys think the weather has when patterning?  I just polished my 870 20ga and my 835 yesterday and wanted to hit the range today, but its cool (40deg) damp  and dreary with light winds.  Supposed to be in the mid 50's tomorrow with sun.  I'm going to wait til tomorrow anyhow.

One of the good things about still target shooting is that we travel, normally from March through November each year to various parts of the U.S. and shoot in lots of different weather conditions as well as different altitudes, etc. We shoot with other folks who use various guns, various different choke tubes and with different barrel lengths.

These events normally begin each morning anywhere from 8:00 a.m. to 9:00 a.m. and may end as early as 1:00 p.m. or go until 6:00 p.m. or so. It may be cool or even cold when we start and then be pretty warm by the end of the day. We'll shoot in light rain and really only quit or suspend shooting in electrical storms.

My point to all of this is that those events really let you see how weather affects patterns. One constant is that cold, dense air really affects the patterns of all guns, turkey shells and chokes. Patterns are more scattered.

As an example at one recent event it was about 32 degrees when we started and gradually warmed to about 70 when we were finished. You could just watch the patterns become more dense as it warmed up during the day.

Warm air and low pressure will affect patterns more than anything else.

As has already been said, it's good to pattern your gun in weather as close to what it will be when you hunt as possible. If you only pattern on warm or hot days, 60s and 70s and you hunt in the 30s and 40s, you may expect more of your gun/choke/shell than it will deliver and that may result in a lost or crippled bird.

Thanks,
Clark

[the Ward]

 :agreed:Very good explanations on the effects of weather on patterns.I too like to try and pattern in the weather conditions i will hunt in,if possible.