Cold Weather LR BR Accuracy Help

[Olde Man]

I am trying to do my dasher seating depth testing and am looking for some 30F + weather. Is the temperature induced velocity variable primarily due to the temperature of the loaded round? Is this something that I can negate or minimize by keeping my ammunition in a shirt pocket and then keep my chamber time to a minimum after shooting an extra fowler. Does the temperature induced velocity change act on the "tune" like a powder charge resulting in the same velocity change. Is this effort going to be useful or just fun barrel time?

 

[Zero333]

Around 30 f it's not too bad with Varget and other temp stable powders.

Once you get below 10 f it's when things really change.

Yeah just keeping the ammo warm will work in 30 f weather, but in 10 f or colder it doesn't work. I tried it. The dope changes dramatically below 0 f with the best of temp stable powders.
I shoot in 0 f and colder temps on a regular basis and even the best of scopes have questionable tracking below 0 f.

 

[Willoughby]

Good info here, I knew temps affected powder , but I also know temps affect the shooters , breathing and not to mention wearing coats and gloves

 

[4xforfun]

Around 30 f it's not too bad with Varget and other temp stable powders.

Once you get below 10 f it's when things really change.

Yeah just keeping the ammo warm will work in 30 f weather, but in 10 f or colder it doesn't work. I tried it. The dope changes dramatically below 0 f with the best of temp stable powders.
I shoot in 0 f and colder temps on a regular basis and even the best of scopes have questionable tracking below 0 f.

Disagree......keep gun warm by firing and keep loaded rounds warm and the GROUP SIZE AND SHAPE will be the same no matter what the temps.

Are the groups going to print in a different place on the target? Absolutely...exterior balistics tells us so....but the size and shape of the groups will remain constant.

Tod

 

[Zero333]

Disagree......keep gun warm by firing and keep loaded rounds warm and the GROUP SIZE AND SHAPE will be the same no matter what the temps.

Are the groups going to print in a different place on the target? Absolutely...exterior balistics tells us so....but the size and shape of the groups will remain constant.

Tod

Group size doesn't change from hot to cold. It's my Dope that really changes. By a crap load of clicks.

 

[dmoran]

12-volt coolers are a good option to maintain ammo to steady temperature zones. Maintaining near reloading room ambient is my suggestion, for both cold and hot scenario's. Even just a regular cooler that starts out at desired ambient, works well to sealing temperature.
Donovan

 

[dmoran]

Group size doesn't change from hot to cold. It's my Dope that really changes. By a crap load of clicks.

Mine can to, depending on the ambient and exposure of the ammo. But can also remain reasonably constant, when I maintain the ammo temperature and limit its exposure.
Donovan

 

[chkunz]

My strategy is not to take gun or ammo out of the house if the temperature is below 40 deg. This works for me and I have never had a ammo problem with this strategy. Below 40 is a good time to prep brass and review shooting diaries and work on position adjustments (on the living room floor with thermostat set to 72). You may disagree but this works for me.

 

[4xforfun]

Group size doesn't change from hot to cold. It's my Dope that really changes. By a crap load of clicks.

Do you heat your ammo/gun? When I keep things hot, my velocity does not change. My POI does due to denser air, but FPS remains the same.

Tod

 

[4xforfun]

Now...there may be such a thing as the actual gun and bedding change due to the cold. You can keep the ammo and chamber /receiver warm, but if the stock dimensions change due to the cold...that is a different animal. Didn't Alex Wheeler just measure a scope change in dimensions the other day and report it here? If the scope can change, then the stock could also.

Tod

 

[dmoran]

Now...there may be such a thing as the actual gun and bedding change due to the cold. You can keep the ammo and chamber /receiver warm, but if the stock dimensions change due to the cold...that is a different animal. Didn't Alex Wheeler just measure a scope change in dimensions the other day and report it here? If the scope can change, then the stock could also.

In winter testing for summer use, I want the rifle exposed for a length of time to the outside ambient, for those very reasons you mention. Only maintaining the ammo to the warmer ambient. But will fire extra sighter's as need be, to aid in barrel control.

Do have to admit, I have done little winter time testing the past few years. Nothing like I use to... lol
My shoot house has had little winter use for some time, other then for storage.
Donovan

 

[4xforfun]

In winter testing for summer use, I want the rifle exposed for a length of time to the outside ambient, for those very reasons you mention. Only maintaining the ammo to the warmer ambient. But will fire extra sighter's as need be, to aid in barrel control.

Do have to admit, I have done little winter time testing the past couple years. Nothing like I use to... lol
My winter shoot house has had little use in some time, other then for storage.
Donovan

I never thought about that....leave em in the cold till they temp stabilize...and then keep the ammo warm and the reciever/bbl hot for testing!

Good stuff!!!

Tod

 

[Zero333]

Do you heat your ammo/gun? When I keep things hot, my velocity does not change. My POI does due to denser air, but FPS remains the same.

Tod

I used to keep the ammo warm but was a real pain in getting things consistent in below 0 f cold temps.

Now I let it get cold and record the dope and envirometals, and sometimes velocity if I felt like taking the chrono out.

This way I get more consistent dope and group size.

When I used to keep the ammo warm, the dope changed in a 10 or 20 shot string.

At 30 f things seem pretty much as usual with only having to adjust the dope a little beyond 600.
Below 0 f, dope and velocity really change.
It's the only time I have to keep track the cold bore shot. And more than 5 minutes between strings it's a cold bore shot all over.

 

[BartsBullets]

Guys I Shoot year around and seldom shoot without a chronograph on the bench. @4xforfun @dmoran

I think zero333 first post is close to spot on. Especially with temps down in the teens, velocities do drop off, tunes change, and groups do not remain the same. To keep the same level of accuracy you do need to adjust your load. This goes for temperature controlled loaded ammo as well.

With that said I don’t think my Grinch or BRAI is effected as much as my 6PPC. In the winter especially with the 6PPC you can’t even reach the normal velocities that you would commonly shoot in the summer, no matter how much powder you put in.

Bart

 

[dmoran]

@Zero333
Believe you and I are talking of two separate scenario's. My input is for testing/load development in cold weather for warm weather use. Totally respect your input and methods to your scenario !.!.!


@BartsBullets
When ambient controlling my ammo (which is preloaded) for testing and/or load development I've been able to get comparable velocity and accuracy from warm to cold. Basically have years of chronograph data (and pressure trace data) proving I myself am able to. Also have a "shoot house" at my range that has aided in my control ability, particularly for pressure traces that demands barrel control for repeatability. Just that I hardly do it anymore, and get lazy to doing any in the winter months... lol

Donovan

 

[BartsBullets]

@Zero333
Believe you and I are talking of two separate scenario's. My input is for testing/load development in cold weather for warm weather use. Totally respect your input and methods to your scenario !.!.!

@BartsBullets
When ambient controlling my ammo (which is preloaded) for testing and/or load development I've been able to get comparable velocity and accuracy from warm to cold. Basically have years of chronograph data (and pressure trace data) proving I myself am able to. Also have a "shoot house" at my range that has aided in my control ability, particularly for pressure traces that demands barrel control for repeatability. Just that I hardly do it anymore, and get lazy to it in the winter months... lol

Donovan

So the same load in 15 degree temp produces the same velocity at 75 degrees? As long as it's loaded in temp controlled environment. I basically tried that with varget yesterday in 14 degree weather. Velocity dropped 40 ft from this fall. I've got a temp controlled building as well.

I can watch the velocity creep up on a 60 to 80 degree day and take a gun out of tune. What I see from most long range guys is they blame an out of tune gun on conditions instead of velocity creeping up.

Now I will say that H4350 seems to be much less effected then any other powder when it comes to temp.


Bart

 

[4xforfun]

So the same load in 15 degree temp produces the same velocity at 75 degrees? As long as it's loaded in temp controlled environment. I basically tried that with varget yesterday in 14 degree weather. Velocity dropped 40 ft from this fall. I've got a temp controlled building as well.

I can watch the velocity creep up on a 60 to 80 degree day and take a gun out of tune. What I see from most long range guys is they blame an out of tune gun on conditions instead of velocity creeping up.

Now I will say that H4350 seems to be much less effected then any other powder when it comes to temp.


Bart

Bart...

Keep your ammo warm and get the gun good and warm by shooting a bunch of sighters. I keep my ammo on the floor of the truck (where it actually gets very warm to the touch) with the heater blowing on it and only take 3-5 out at a time and keep them in my inside shirt pocket. I park 6 feet from my bench. Single feed from my shirt to the load port and shut the bolt. I don't worry about the whole "don't leave a loaded round in the hot chamber" thing in the winter like I do in the summer. And, no breaks....keep on shooting...don't let the gun cool off. Keep it warm. Velocities are constant with summer tests.

Now like Donovin said.....for cold weather hunting guns and winter shooting purposes.....cold ammo and cold BBL. Test em like you're going to shoot em....COLD. BIG DIFFERENCE between 80 and -10!!

And...Donovin and I live in North Dakota where the winter weather lasts FOREVER, and would kill most of the southerners around this fourm!! Well, I do at least....Donovin lives in the "deep south" part of North Dakota. That's where we go for winter vacation.

Have a great weekend,
Tod

 

[BartsBullets]

Bart...

Keep your ammo warm and get the gun good and warm by shooting a bunch of sighters. I keep my ammo on the floor of the truck (where it actually gets very warm to the touch) with the heater blowing on it and only take 3-5 out at a time and keep them in my inside shirt pocket. I park 6 feet from my bench. Single feed from my shirt to the load port and shut the bolt. I don't worry about the whole "don't leave a loaded round in the hot chamber" thing in the winter like I do in the summer. And, no breaks....keep on shooting...don't let the gun cool off. Keep it warm. Velocities are constant with summer tests.

Now like Donovin said.....for cold weather hunting guns and winter shooting purposes.....cold ammo and cold BBL. Test em like you're going to shoot em....COLD. BIG DIFFERENCE between 80 and -10!!

And...Donovin and I live in North Dakota where the winter weather lasts FOREVER, and would kill most of the southerners around this fourm!! Well, I do at least....Donovin lives in the "deep south" part of North Dakota. That's where we go for winter vacation.

Have a great weekend,
Tod

Tod,

I think you can help stabilize loads with what you’re doing. At short Range matches I load in a heated air conditioned trailer. Here at home I have a heated and air conditioning shooting building with bench. With all that said I see significant changes in velocity due to temp and I do need to adjust the load to keep the gun tuned to shoot it’s best.

I'm not knocking anyone's technique if it works go with it. But it's not what I've observed.




.

Bart

 

[4xforfun]

Tod,

I think you can help stabilize loads with what you’re doing. At short Range matches I load in a heated air conditioned trailer. Here at home I have a heated and air conditioning shooting building with bench. With all that said I see significant changes in velocity due to temp and I do need to adjust the load to keep the gun tuned to shoot it’s best.




View attachment 1031284 .

Bart

So..you are saying that you load and shoot out of a heated building, and you see reduced velocity in the winter?

 

[dmoran]

@BartsBullets
Great setup.... nice picture !.!.!
How do you deal with "window mirage" (where the warm air/cold air meet) on cold days from a heated bench?
Up here, not even sure I can call it mirage, its so bad, if I try having my shoot house warm.... lol
Donovan