Temperature effects

[338 dude]

that is why a kestrel 5700 is a good thing to have

Any Kestrel is a must-have for any long range shooting

 

[338 dude]

So if I'm trying to get the Dope on my load for hunting season I need to wait till the temperature drops? At what temperature will the effect be minimal?

As stated earlier load your dope you're running now into a ballistic program adjust the temperature to the average temperature during hunting season this will get you very close if you don't have any of that stuff I would say 50° or less will get you in the ballpark

 

[BrentM]

Let's review a couple of things:

internal ballistics- everything going on inside the rifle. This is things like powder temp sensitivity, standard deviation, and barrel harmonics. With today's powder options a long range hunter should be using a temperature stabile powder. If not, then you have to know your ammo's rate of change in the conditions you will be in. If you work up a load in 90f temps and hunt at 10f what is the affect? If the powder is stabile the affect is very very minimal. Maybe .2 moa. If the ammo has a 50 FPS difference due to this temp swing your impact change will be around .7-1 moa.

external ballistics: everything outside the rifle. So once your bullet leaves the barrel it's fighting gravity and atmospherics. Temp, humidity, and elevation determine air density. The more dense the air the more negative the affect, the less dense the less the affect....similar to more of less wind. This is where a weather meter comes into play. You need to have proper inputs that get you close to current atmospheric conditions.

In the end all of this data, plus some, will be part of your routine for collecting a shoot to solution. Dope is going to come from testing yourself and rifle in the conditions you will shoot in and then applying that knowledge when the time comes to squeeze the trigger. The better the data, the more the data, the more precise your solution is going to be.

 

[Oklahunter1]

Thanks to everyone for your help and input. I learned a lot!

 

[Tommytrees]

Some powders are affected and some aren't, and some more than others. As @Tiny_Tim mentioned, there are some that wont be affected by the rise or drop in temperatures. Even 22lr ammo is affected by temperatures.

As an example, shooting silhouette with my 7mm-08 I use IMR-4350 with 150gr Sierra Matchkings. Not a temp stable powder but also no too temp sensitive. If I start the match at 9 am at say 80 degrees, at the 200m targets I'll have no issues, but by 2:00 pm when its 105 degrees or higher and shooting at the targets at 500m I'll be hitting 5" to 7" high. Now I know this by experience from many years of shooting silhouette competition and taking lots and lots of notes.

Powder sensitivities vary so POI will vary from powder to powder, that's why its important to take notes when at the range like temperature, wind speed and direction, himidity, altitude, etc.

This is how you will learn how your loads and rifles behave.

Now there are some tricks that help when shooting a match or practicing at the range when it's warmer. I keep my ammo on a small cooler with ice packs. This keeps the ammo cool and dry. However, as you shoot your chamber and barrel gets warmer and warmer so there might still be some change in your POI, again that why notes are so important.

Hope this helps and stay safe.

OK, don't laugh at the new guy, but what if you use a thermometer and keep the ammo at a temp that falls in that range that you may hunt and use a battery powered air pump to blow down the barrel for say 4-5 mins, while you bring your dope book to date.. that would allow more time for barrel to cool and more closely duplicate conditions.
MAYBE !

 

[BrentM]

OK, don't laugh at the new guy, but what if you use a thermometer and keep the ammo at a temp that falls in that range that you may hunt and use a battery powered air pump to blow down the barrel for say 4-5 mins, while you bring your dope book to date.. that would allow more time for barrel to cool and more closely duplicate conditions.
MAYBE !

Yes you can play with powder temp by chilling the ammo until ready to fire. This will give you close muzzle velocity by You cannot duplicte atmospheric. You'll still see an increase in speed down range.