If so, what is your technique and how much per 10 oF change from say 70 oF?

Yep sometimes. Hunting deer and elk etc I don't normally worry about it. Long Ranch varmints might need an adjustment. If you are planning more than 400-500yd shots then you probably need to adjust.

Since any change is going to be based on your rifle, powder, bullet etc. Only way I know to adjust is simply test fire at the temp and range I'm shooting. I guess if you can make a drop chart for your rifle you could make a temp one as well.

Paul,

I assume you use ambient temperature as your ammo's temperature - some advocate infrared thermometers...but that seems excessive to me.

I've been using QL with its temp correction feature...which has been ~20 fps per 10 oF. This seem reasonable to me.

It hard to develop a temp correction chart where I live.

Regards, AIU

quote:

I assume you use ambient temperature as your ammo's temperature

AIU
As I said for most shooting and hunting I don't worry about any temp correction. My norm is to (if possible) Simply do a sight in check when I go hunting. That corrects for temp and altitude. In my long range PD rifle I might take a couple shots if the temp is significantly different than when I worked up the load. On my shorter range 223 I don't worry about it.

20fps seems a little on the high side even for something like RL22. But I haven't done a huge amount of specific testing on the issue. There is a long thread about temp sensitivity down on reloading.

Infrared Thermometer??? Simple ambient for me.

In a normal hunting rifle at the ranges I normally shoot I've simply not seen enough difference to worry about.

What to the 1000yd boys do?

I found this article real interesting. Here is what he said about temp and 1000yds, http://www.6mmbr.com/gunweek053.html

Temperature changes--how do they affect bullet trajectory, and is there a way to compensate for this?

A: Normally if the temp change is less than 10 degrees I don't worry too much. In the short periods of record fire that we shoot you won't get a 10+ degree temp change. The temp-related elevation change that can occur in actual string duration is pretty tiny. But I will check my vertical zero with each course of fire. But even from 60 degrees to 80 degrees it's still in the 10 ring on a prone target.

Can't provide scientific data, but shot long range,1000yd. and Palma Matches, for quite a few years and old rule of thumb is that if you start the match in the morning, say 9am @ 65deg. and in the afternoon temp is up near 90F, you will experience change in elevation. Always kept ammo out of direct sun light for obvious reasons. Supposedly each increase of 15deg. could alter as much as 1moa elevation change. During these matches you may be on the first relay and then do pit service and not get back to the firing line until mid day with increased temps. and you will note an increase in elevation. At 1000yds. 1moa is equivalent to 10" which would take you out of the X ring or even 10 ring. Some matches do not permit sight in shots other than first relay and you are on your own for the other two relays. Keeping this in mind I would adjust down 1moa just to check it out. Just my experience.

I think there's only a handful of long-range shooters posting here...I think AR has become mostly an Africa sport hunting and outfitter forum.

The biggest contributor to elevation changes due to temp is a combined effect of warming or cooling air- everything changes POI as atmospheric temp changes- pressure ( due to temp, humidity).

The snipers rule of thumb for 308/762 LR ammo ( 175 SMKs at 2550) is one MOA for 20 deg F in temp, and one MOA for every 20 % change in RH.

Knowing which way to correct is the key-these factors often cancel each other as well as compliment each other. Ammo temp is fairly easy to correct for- use temp insensitive powders ( Hodgdon extruded mainly).

Keep your ammo out of the sun and it should not make much of a difference compared to atmospherics.

Best practice is to know zeros at known distance under warm or cool conditions, then correct for atmospherics.

Example- I know my AR 223 Wylde service rifle zero at 600 varies by 1 MOA per 30 deg F ambient temp change (varget and 80 Amaxs at 2830) but it is not due to muzzle velocity ( chronograph reading at 20 and 90 deg F is within 6 FS SD)- but rather air density so I do not worry any further-just add 4 clicks and shoot 10s and Xs.

At 1000, I do more.

Well, I used to have a house in MN and shot year round. Two lessons I learned:

1. Most ball powders are extremely temp sensitive
2. The lower the BC, the more it is impacted by temp.

AIU: Based on your recent posts, it seems like you are trying to acquire long range shooting skills through either buying technology or leveraging other's observations. Nothing wrong with that; I do the same myself. But it is no substitute for practice. If you don't have a place to shoot at long range weekly, I don't think you will ever be a good long range shot and frankly, buying all the gear is a waste of money.

From a pure hunting standpoint, it is far better to be able to shoot something quickly at a reasonable range than be able to kill something at 800 but take all day to get into position. I saw a guy on a long range show the other day shoot a moose from 295 yards but he had to pull out a bench type tripod and shoot prone to do it. If you can't put your arm through your sling, sit down, tighten the keepers, and whack that moose in about 10 seconds you need more practice.

I was bear hunting in AK last year and my guide told me about a hunter who bought the whole Gunwerks package. They saw a bear at 550 yards and the hunter was convinced he could kill it. He never even hit the bear.

AZ,

I've been shooting all my life very long range without the fancy equipment - that is, in excess of 500 yd with no missed shots yet at big game, although the overwhelming majority of my kills are within 300 yards.

I grew up in Wyoming hunting prairie dogs and antelope at long range, and I have hunted extensively all over the Rocky Mountain West.

I used to shoot prairie dogs as far away as possible, which was usually 400 to 600 yds. But, this sometimes took a couple of shots to get the wind doped. I've lost count how many I've killed, Wyoming has too many prairie dogs.

I've also killed many coyotes at very long range, sometimes on the run.

My last public land mule deer buck was taken at 515 yds using a B&C reticle on a 30-06 AI (165 gr Accubond). I used a chronograph, Leupold range finder, published Nosler BC, and the info provided in the "Leupold Ballistic Supplement" booklet.

I'm thinking it might be even more fun - and easier - with the latest technology. I got excited about it after reading Brian Litz's books, and I'm not intimidated by technology or computers - in fact, I find them fun and easy to use.

Who knows maybe I'll be forced to take a shot well over 800 yds. By "forced" I mean it's impossible to get closer.

I've got excellent equipment with my guns being made by a well-known benchrest gunsmith. I have two benchrest guns and have learned to read the wind and conditions, while shooting for groups in the 0.15 inch range.

I'm asking questions here to get some opinion as to which Kestrell would be the "best buy" - I've been using the standard wind estimating skills based on tree leaves, limb sway, etc.

Brian Litz's books and the internet cover most aspects of extreme long range shooting quite well, but asking here may produce some useful info and reinforce many of the skills I've already developed.

Maybe we'll get to compete against each other in a benchrest or LR shooting match. I think it would be fun.

Well, I didn't mean to offend you; I was simply saying the best way to learn all of this stuff is just go out and shoot at long range. A lot. I do shoot at 800 yards - every week, sometimes multiple days. It has taught me there are a lot of things that can go wrong at 800. In fact, 600 is chip shot compared to 800 (depending on the bullet, of course).

I do agree Brian Litz is the man when it comes to a lot of this stuff; I have certainly learned a lot from him. And I have learned a lot from AR members as well.

Have no experience in shooting "sporting arms" at game in extreme ranges, but can say have sent fair number of rounds downrange for "targets." The most challenging match for me has always been the Palma Match which is shot at 800, 900, & 1000yds. 308 is the round of choice but other calibers can be used, but would disqualify you from any possibility of winning(placed high in several, but never won a Palma.) 15rnds/each distance or total of 45 for possible score of 450. Best for me was 443/18x's and number of shooters shot better scores, real hard core shooters that day.
You get past the 800yd line with the 308 you are pushing it and better have your "chit" together and would also say that if you do not clean the 800, it only gets tougher at 9 and 1000yds. I would routinely clean the 800, start dropping points at 900 and of course dropped some at the 1000yd. line. Never cleaned the 1000yd line with the 308, did once with 300Win. Mag but that was a fluke or just luck. If you like shooting long range, give Palma a try with the 308 and keep in mind that only micrometer/iron sights permitted and from prone/sling position. It's a real challenge to control that little bullet at those distances but will say can't think of a better way to develop skills and education on shooting long range. I would not go so far to say that the 600yd line is a "chip shot" but would shoot in those matches for warm up so to speak with a Palma Match week or so away. Generally used the M14 platform for the 600 matches and can say won my share of those, but not the best platform for longer ranges. Older now, bad knees, kidney stones, etc. and don't participate anymore, but do help new shooters out as much as possible. Find you a regulation 600yd target, and practice "playing in the X ring." Fortunate to have had some "time behind the gun" with very skilled shooter several years ago(he is now shooting at the big range in the sky where the conditions are always perfect!) and game was to shoot a 12 o'clock X, then at his direction, shoot a 9 o'clock X, 6 o'clock and then a 3 o'clock. Fifth shot to be a "pinwheel" X/dead center. When you can do that you are on your way to "bigger and better scores" and you have also worn out barrels, many pounds of powder/bullets but lots of fond memories.

AAZW,

I would find it hard to consider it a simple "chip shot" to hit a prairie dog (3 x 8") in the usual 10 - 15 mph Windoming crosswind at 600 yds with a 22-250 (55 gr bullet) on the very first shot. Moreover, in a significant crosswind, it's the 3" that's hard to hit on the first shot.

If you can do that, I'd be impressed, and your self-confidence would be justified.

Mentioning the size of a "critter" being 3x6" would be close to the size of the X ring for 600yd target and with the wind speeds shown, that would be tough for 22-250 and 55gr bullet.
Sorry for straying from original subject, but as one of my last efforts for long range match shooting, built a Rem.700 with 30" barrel/Krieger in 22-250 and 8 twist for using the 80gr SMK's. Found that this combo very similar to the adjustments for both elevation and wind of the 308 using the SMK 155 Palma bullet, but with very little recoil. Could get a bit more but at just over 3000fps was very accurate. Now have Ruger No.1 in 22-250 but twist is just under 7 and works well with both 80gr and 90gr SMK's. Rifle is set up with Unertl 16X and definitely a fun gun to shoot.
Promise I will no longer stray from the original subject, but long range shooting stirs my emotions so to speak.

I shoot to 1,000 yards almost every month and I don't compensate for temperature specifically.

I shoot my sighters before and during the match and that gives me any adjustment that I need.

There is a difference of about 1/2 MOA (5") at 1,000 yards between my winter (40-50 degrees) and my summer zeroes (80-90 degrees)

quote:

Originally posted by Ackley Improved User:
AAZW,

I would find it hard to consider it a simple "chip shot" to hit a prairie dog (3 x 8") in the usual 10 - 15 mph Windoming crosswind at 600 yds with a 22-250 (55 gr bullet) on the very first shot. Moreover, in a significant crosswind, it's the 3" that's hard to hit on the first shot.

If you can do that, I'd be impressed, and your self-confidence would be justified.

Don't be, because I can't do it. But if the target is 10 inches wide, I am pretty confident. But at 800 it is far more difficult. A 300 gr 338 bullet makes it easier, but even it isn't a magical solution - at some point, the wind drift in any bullet basically eliminates your chances of a 90 percent first round hit. That is why in your question about the 800 yard canyon shot, I would take the rock shot. My second round hit rate is above 90 percent, and I would guess the odds of the animal not running away are less than the odds of missing the target.

By the way, I have tried those light bullets during our 500 yard gong shoots - any wind really blows them around. Move up to an 80 gr AMAX, and you are talking a whole new ballgame though.