Barrel length

[allaboutshooting]

In patterning I want to mention one more thing.  How many pay attention to outside air temperatures when patterning their guns?
I know Clark mentioned 60-70 degree temps for factory testing muzzle velocity but I have also noticed a huge difference in my patterns when I was testing various loads in colder temps 30-40 degree air temps.  Those who live south may not see this but here in Southern IL when it's still possibly cold in March/April I was shocked at the difference in patterning.
I have seen guns that had a devastating pattern at 40 and 50 yards in 70 degree temps that were borderline of being the same at 25 to 35 yards with air temps being 30-40 degrees.
It was amazing to see the difference barrel and air temperature can make in a pattern.  I don't duck hunt very much anymore but we even experimented with our loads and chokes at different air temps as well for this years back and it is an eye opener.

The differences are very dramatic. When you pattern in the low to mid-50s as I've been doing, pellet counts go way down, even from the low 60s. When you get in the high 60s and 70s the differences can be almost unbelievable. All too often folks pattern in the summer or when it's warm and never pattern when it's cooler.

Velocities are also lower when it's cooler. That terminal velocity that was more than enough to kill that gobbler at 60 may be marginal at best at 50. I see that so much when I look at the backing for my targets when it's cooler and see pellets still in the backing that were fully penetrating it in the 60s.

Thanks,
Clark

[Tail Feathers]

I try to pattern mine in temps that resemble my local spring morning temps.
It was 62 the other day and that's close to mid-season temps.
I do want to pattern it again in temps around 50 degrees to see what the change is, just so I'll know.
I'm not likely to see temps much lower, at least not where I'll be hunting this spring.