Home Forums Hunting & Shooting Ask The Gunwriters The American Rifleman has a newer Field Editor

John, your point about the shift in POI really got me thinking about it in relation to shotgun slugs. We always sight-in sometime in October or early November on a day when the temperature is well above freezing. We then head out in early December when the temperature might be anywhere from 65 (rare) to below zero. I still beat myself up over a very nice buck that dropped at the shot and then got up and headed through the trees (a couple of which I shot) and out of my life. (We followed him up for better than a mile before losing the trail in a hay field. A neighbor later told us of finding a large body that someone had cut the head off of another mile or so from where we lost the trail.) I have always suspected that I hit above the lungs and below the spine. While the poor placement could have been entirely my fault, I now wonder how much the cold might have had to do with POI. I suppose that I could run some tests in cold weather, but the cost of saboted slugs and the prospect of frozen snot all over the gun and surroundings leaves me cold, so to speak. I guess we could at least check sights the day before season if the temperature is vastly different than when we did the initial sighting-in. As always, you've given me something to think about. Thanks, John

JB, Copngratulations on the new position!

Mark, thanks, I'll follow up with that next time I'm at the range.




Mr. JW,

We are not your snivel little boys here, and we are having fun. We might take our art & science a little more serious than most though.
Point is, we bring home the bacon more times than not and there is a good reason for that.

Mule Deer,

Does using a Magnum Primer help loads not be cold sensitive?

Spot

5sdad
"I have always suspected that I hit above the lungs and below the spine."

There is no such place... Lungs are well wrapped around either side of the spine and there is no "void" ever. Bullets sometimes move stuff away from in front of them as they go through and lungs may be aparently uninjured after a bullet went through a bit high, but there is still no vacancy there.

If gases were present behind a lung those gases would expand far more readily than lung tissue and reduce breathing efficiency greatly...
art

idahoguy,

Thanks very much!

But actually it isn't really a new position. I was a Field Editor for both American Hunter and American Rifleman for several years in the 1990's, and only resigned when I got buried with work from higher-paying magazines.

However, when Wolfe and I parted a year ago, one of the first editors I called was Mark Keefe at AR, the same guy I worked for a decade ago. Mark hired me back right away. He is great guy to work for, and fun to hang with too, when I get the chance. He knows a lot about guns and has a wicked sense of humor....

Sitka,

You're right, of course--but I did some research a number of years ago after hearing about the "gap" from several hunters.

It turns out that there is a surprising chance of an animal surviving a hit at the up edge of the lungs, just under the spine, because apparently the "air pressure" around the edges of the lungs is slow low, and the capillaries so small.

In fact, some species of big game seem to be able to survive such as hit better than others. I have encountered more than one dead elk that had a healed bullet wound in exactly that place, but the only deer I've seen that survived it was shot with an arrow. One of my PH's in Africa said that it's common for gemsbok to survive being shot high through the lungs, just under the spine, because he has seen a number of them killed with the same healed wound I've observed on elk. So while the gap is mythical, big game can and does survive such a hit.

I just got the new issue and have not read it yet.
But I was wondering how much the tempiture change in its own right might change the velocity.
meaning at least some of the 150 Fps is likly do to lighter and dryer atmosphere. I would think that makes some difference.
mabye not even enough to wonder about. I am no physisist, and can't even spell it.
But 70 degrees makes about 150 FPS difference , in total, but The change may not all be in the internal balistics. some might be in the external.
...tj3006

Art, interesting. Thanks for pointing that out. I thought that I had read somewhere that there was a void there. Sure wish I knew for sure where he was hit. He went down in a heap, wasn't limping, and the blood was definitely not from the digestive tract. Wonder if it was neck. Best, John

I just received the AR today and scanned through it. Saw JB's article on temperature, but have not read it yet. The article appears to be one of completeness and throughness (just like we expect of JB). I learn from such articles.

JB
We have had this discussion before obviously and you make great points... High in the ribs is a bad place to go. I have seen moose shot there and the lungs appeared unscathed and it seemed impossible for a bullet to have gotten through them without making a hole...

tj
"... at least some of the 150 Fps is likly do to lighter and dryer atmosphere."

Just FYI... a great bar bet is the fact dry air is heavier than wet air.

The proof is simple though. A gas at a given temp and volume has the same number of molecules in it, (almost) no matter how heavy the molecules are. Replace the Nitrogen (79% of air) or the Oxygen (21%) with water vapor and you are replacing molecules weighing 28 and 32 grams per mole respectively with molecules weighing 18gpm...

Cold air is denser than warm, too, so winter dry air is usually considerably heavier than wet summer air.
art

I read the article last night and enjoyed it from beginning to end. Good one, John.

Steve

Thanks, Rooms!

Neat thread. I'm a little behind on my AR and AH reading. I'll have to check this one out. I often let my mags "pile" without reading, and then take several with me to Dr's appointments and the barber shop so I have some decent material while I wait.

This past fall I was using Federal premium loads in my 7-08. I sighted in in 85+ degree weather. When I got to Canada, I checked zero in 45 degree weather but at 5000ft higher elevation. I was suprised to have a 1.5 inch drop at 100 yards in Canada.

It's possible the scope could have gotten off in the plane trip, but I would guess the powder Federal uses in that load was pretty sensitive to the temp change.

Maybe, or maybe it was the plane trip. I have done dozens of plane trips and sometimes there's a POI change at 100 yards and sometimes there isn't. In the same weather conditions it has gone both ways, with good scopes and mounts,

That't the reason that I sight in the rifles used in my tests at 70 degrees at the very latest time possible (usually October) then don't touch them until it gets down around zero, which can happen anytime from November on here. Actually on rare occasions it happens in late October.

I seem to recall reading of differences between single and
double based powders at cold temperstures. Any input on
this?.
I didn't know that Mule Deer was with the Rifleman, I will
have to rejoin.
Good luck!

Altitude has an effect too on air density and thus drag and trajectory. 5000 ft is a significant density change.

hawkins,

The two most temp-resistant kinds of powder I have found in my tests are Hodgdon Extremes (single-base) and the Ramshot line of ball powders (double-base).

Among the powders that have eally reacted to temperarture change are some of the IMR's (single-base) and some of the Aliant Reloder series (double-base).

So I don't think there is any hard rule about either type.

I just finished the article and as always with JB's work it was well thought out, nicely written, and informative.