Will Temp Effect POI?

[Spring Creek Calls]

I was not able to do any kind of in depth POI testing this fall with my 1300 and the LB's. I know the temp will affect my pattern #'s and density, but will it effect POI? Thanks!

[Snoodsniper]

Yep

[USMC0331]

Yes.

[allaboutshooting]

I was not able to do any kind of in depth POI testing this fall with my 1300 and the LB's. I know the temp will affect my pattern #'s and density, but will it effect POI? Thanks!

I see you've already had some replies and they may well be correct.

Frankly, I've never thought much about temperature affecting point of impact of a sting of shotshell pellets. As you've noted, ambient temperature will affect patterns because warmer air is less dense than cold air. I can't say that I've ever personally noted a difference in point of impact when shooting in cooler morning temperatures and shooting in warmer afternoon temperatures, much like we encounter many times in still target shoots. Then again, I've not given that any consideration.

I have learned that shot pellets behave differently than most bullets due to their shape. Spheres don't really fly very well and lose speed very rapidly. Most of my shotguns print about the same at 20 yards as at 40, unlike rifle bullets or shotgun slugs.

You've raised a very interesting question. I suspect if their is a difference in the POI of the "core pattern" it might have more to do with air density disbursing it than anything else.

I was recently sent a copy of "Gun Digest Guide to Modern Shotgunning" by L.P. Brezny. He may know as much about how shotgun pellets behave as anyone alive today. I'll see if he has anything to say on that subject in the book and if not, I'll give him a call.

I can also research work done by the engineers at Olin/Winchester. Many years ago their work was published and it contains a wealth of information about how shotgun pellets react to air density and temperature. That work was done mostly with lead pellets and as I recall some with steel but the principles would still apply.

I appreciate your bringing up the subject.

Thanks,
Clark

[dirt road ninja]

Shot mine at near 100 degrees and at 40 degrees. No difference in poi. Maybe if you froze the shell to well below 0, but I can't see it making much if any difference from 0-100*.

[Spring Creek Calls]

Thank you all for your replies! I shot the LB's at big paper last fall to analyze  pattern performance but did not get an opportunity to shoot off a solid rest to test POI before the cold weather sat in. I'd like to accomplish this now as my shooting areas are also my hunting areas. I may add a red dot to the 1300 even if the POI is good as it will help with the close turkey shot and I'm having trouble picking up the rifle sights on my slug barrel.

Would also enjoy any info that Clark may find in his information. Thanks!

[30_06]

I've never done a proper scientific test, but can't say I have noticed a difference in temps ranging from 19degr-91degr. Density has changed, but not POI.

[allaboutshooting]

Thank you all for your replies! I shot the LB's at big paper last fall to analyze  pattern performance but did not get an opportunity to shoot off a solid rest to test POI before the cold weather sat in. I'd like to accomplish this now as my shooting areas are also my hunting areas. I may add a red dot to the 1300 even if the POI is good as it will help with the close turkey shot and I'm having trouble picking up the rifle sights on my slug barrel.

Would also enjoy any info that Clark may find in his information. Thanks!

As I'm sure you know, the subject and study of ballistics on shot is quite different from that of conical bullets. There are some true recognized experts in the field of course and published work on the subject. For many however, a shotgun has always been a "scatter gun" and the behavior of individual pellets has not been a subject of great interest. We as turkey hunters are probably more interested in and do more patterning than any other group of shotgunners, since we shoot them more like rifles. The "stinging" of shot was little understood for many years, for example.

I can find no information that directly addresses the subject of POI changes of shot strings due to temperature variances other than the fact that the density of cooler air will cause a pattern to degrade more than it will in warmer air, all other things being equal.

Round balls, like shot, don't behave like conical bullets of course and lose velocity very quickly. The faster they are launched, the faster they lose velocity. The "Georgia Project" conducted by a group of ballistic experts and using both high speed cameras and Doppler radar (among other devices) was quite revealing about the behavior of shot and that of different configurations of chokes on shot wads and shot charges.

I will need to review the much earlier work by the Olin/Winchester engineers but my recollection is that no reference was made to the subject of POI except as it deals with the effect of wind on a shot charge.

I believe that you will not see any difference in POI but in differing temperatures. You will of course see sometimes very dramatic differences in pattens however.

Thanks,
Clark

[Spring Creek Calls]

Thanks Clark! I did not want to go thru the hassle of winter range shooting if my efforts would be useless come spring. I'll wait for a calm 30+ degree day and give it a go.

[dirt road ninja]

Agree or disagree with Mr. Clark, he always seems to take the time to answer a question or concern thoroughly. A wealth of knowledge on turkey guns. Thanks for your time sir!

[Ihuntoldschool]

No, not enough to notice

[allaboutshooting]

You're welcome. I hope some of the information was helpful.

Thanks,
Clark