Temperature for Cold Bore shot

[GAgunLAWbooklet]

I have a question for all sniper long range tactical types, and long range hunters who expect to put a bullet in a deer's heart from 500+ yards with the FIRST SHOT OF THE DAY.

Again, this is NOT about what kind of groups you shoot at the range after you've warmed up and had some sighting shots to get dialed-in.

First shot of the day, cold bore only !!

WHAT DO YOU DO ABOUT FLUCTUATIONS IN TEMPERATURE from the last time your rifle was zeroed?

SCENARIO:

You zero and practice with your rifle on nice days when the outside temperature is between 60 and 90 degrees. Let's go one step farther and say you're a SWAT team member who goes to an indoor police range every week and fires a couple of rounds through the sniper rifle to just "check the zero" at 25 yards. It's always good. But the temperature inside that range is always in the 60s or 70s, any time of the year.

One day, you get summoned to take an important, life-saving shot (or, if you're a hunter, that once-in-a-lifetime trophy animal) from 600 yards. No practice shots. This will be the first time in a week that you've pulled the trigger on this rifle.

TEMPERATURE: It's 25 degrees outside. This is 40 degrees colder than the last 3 or 4 times you've shot this gun.

Will that throw off your point of impact?

OR, suppose it's TOO HOT: Let's say you zeroed your rifle on an April morning, on a nice day when it was 73 degrees at the time you were at the range.
THEN, you don't touch the rifle until you get called-out to make a critical shot in JUNE.
It's mid-June, and it's 2 p.m. The air temp is 95 and your rifle is in the sun, sitting on a black range bag. Your gun is getting super-heated just from the sunlight.

Will that throw off your point of impact?

How do you snipers, tactical long range shooters, and extreme long range hunters, deal with this?

 

[bulletpaluza]

Well this is the reason snipers keep a shooting log with their rifle. Every shot taken from after barrel break in is recorded along with temp humidity and distance and moa off from point of aim yadda yadda. Every "snipper" will have a similar book so when they show up on scene they can reference past shots to put them on target faster.

I keep a similar book but less detail and i never clean my bore of my precision rifle only the chamber and I hand load for it to get the best results possible.

 

[GAgunLAWbooklet]

And will you intentionally make some trips to the range on remarkably cold days, and hot days, and dry days, and humid days, just so that you can get this data into your book?

 

[REDX]

That's where your Ballistic app comes into play. Plug in your variables and go. If you know you are going to be hunting in a certain environment you can make up pre printed cards.

 

[CBeck]

if your ammo has velocity variations due to temperature you account for that and the environmental score your dope but I don't I don't see any variation in my 100 yard zero from temperature variation. I do get some beard shift from time to time.

 

[REDX]

100 yards will hardly change enough to worry about for hunting but at 500 yards you will see temperature and Humidity effects even with temperature stabile powders.

 

[bulletpaluza]

And will you intentionally make some trips to the range on remarkably cold days, and hot days, and dry days, and humid days, just so that you can get this data into your book?

I'm no sniper but I do shoot year round.

 

[REDX]

And will you intentionally make some trips to the range on remarkably cold days, and hot days, and dry days, and humid days, just so that you can get this data into your book?

Just plug in good data and you should be good to go. I shoot from High altitudes and low temperatures to Sea Level and 96 degrees, and my kestrel is spot on.

 

[cmshoot]

1. If you're an actual Sniper, you collect actual shooting data in every weather variable you can.

2. You can use a ballistic app if you don't have actual data, but I prefer actual data.

3. If you don't have a ballistic app (or even if you do) you can use mathematical formulae to compensate for changes in temperature and altitude. We Snipers were doing this looooong before ballistic apps became available.

The actual temperature of your rifle and/or ammo won't change the POI near as much as the change in temperature of the air. 2 factors are ALWAYS present when you fire a shot; gravity which starts to pull the bullet down as soon as it exits the muzzle, and air density which causes drag which slows the bullet down. The 2 factors which effect drag the most are temperature and altitude. The colder the air, the denser the air is, and therefore the more drag that is present effecting the bullet. The higher the altitude, the thinner the air, so the less drag effects the bullet.

 

[REDX]

Hard data is nice to have IF you can get it but sometimes its not possible for the average person to collect hard Data for every single situation, that's where the math formulas, data cards and apps come into play.

I know/worked with plenty of Snipers that use their apps first and place the confirmation info into their data book.

Everybody has their methods.