Cold Weather LR BR Accuracy Help

[BartsBullets]

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

Yes Sir!

 

[dmoran]

@tom
Knowing your one to "cooler control" your ammo, how much velocity spread might you see in your pet-loads going from say 25 to 75-F when doing so?
Donovan

 

[Alex Wheeler]

A lot of Deep Creek guys load at the range. I dont know if other long range guys are doing it or not honestly. They should. I was on rl15 in my dasher and loaded a different charge every match day, we dont have time to load between targets or clean with pit duty. Even during the day if it dropped off I would go out of tune and in one case held my records cases in my hands to warm them up and fix some bad vertical from a cool off. I believe the temp of the ammo plays the biggest role. An ice cold chamber will suck the warmth out of a case fast though. I started the season .5 grains less than I ended it. While deep creek has its benefits you will shoot in temps from zero to 90 degrees over the course of the season and a 40 degree swing in a day is not uncommon.

 

[4xforfun]

Yes Sir!

So how does your ammo know weather it is summer or winter if you are loading and shooting in a controlled environment?

 

[BartsBullets]

@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

Donovan,

Window mirage is a big problem. A fan blowing across the barrel and out the window for a bag gun helps. But you still have to deal with mirage.

Durning the winter I shoot my rail guns a lot! The rail is return to battery. Mirage is no problem with it. I have 2 1/2 Jay Young rails (2 complete rails with and extra top) plus a Don Powell rail, so basically 4 different rails I can test bullets with. I have to be able test Bullets regardless of the weather.

Bart

 

[BartsBullets]

So how does your ammo know weather it is summer or winter if you are loading and shooting in a controlled environment?

Tod,

It doesn't! But the bullet pushing the air column out of the barrel and then flying through the atmosphere does! Trying to keep your ammo at a constant temp helps but it's not the ultimate answer for tune or maintaining velocity for that matter.

Bart

 

[22BRGUY]

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.




View attachment 1031284 .

Bart

Beautiful set up. I could definitely relate to the reasoning for the blue X on the window.

 

[Alex Wheeler]

Bart, you coming to the 1k nats? I would like to see what a tuned dasher/BRA could do at 1k in a rail. I have a guess, but it would be cool to see.

 

[BartsBullets]

Bart, you coming to the 1k nats? I would like to see what a tuned dasher/BRA could do at 1k in a rail. I have a guess, but it would be cool to see.

Alex,

I was hoping to make it. We were going to turn it into a Griswold Vaction! But your guys Nationals 10 Aug are right on top of the IBS Nationals which start 13 Aug, so no 1000 yard Nationals for me this year!

With the right barrel I think a rail would shoot great at a 1000. I'm pretty sure that's contrary to your inital thoughts since the rails are so stiff. But really is there that much difference between what I'm shooting and these 1000 yard HV guns? It will be interesting to see!

 

[4xforfun]

Tod,

It doesn't! But the bullet pushing the air column out of the barrel and then flying through the atmosphere does! Trying to keep your ammo at a constant temp helps but it's not the ultimate answer for tune or maintaining velocity for that matter.

Bart

Hogwash. There is no cold column of air inside the barrel.... the air in the barrel is hot due to the temperature of the barrel. And the bullet flying through What atmosphere? The Magneto speed is 3 inches from the end of the barrel. You are correct in that downrange velocities will be reduced due to the denser air

Tod,

It doesn't! But the bullet pushing the air column out of the barrel and then flying through the atmosphere does! Trying to keep your ammo at a constant temp helps but it's not the ultimate answer for tune or maintaining velocity for that matter.

Bart

The column of air inside the barrel is hot summer or winter. Keeping your Barrel hot ensures the column of air inside the barrel will also be hot, so the air density would be the same inside the barrel. And as far as the bullet flying through the air ....how much affect could cold weather have on 3in of space between the muzzle and my Magneto speed? You are absolutely correct in that the point of impact will be much lower due to the denser air, but velocity , and the group shape and size will remain constant. Interior ballistics will be identical.... exterior ballistics will be different.

 

[ljmontano]

I shot last week and the temp was in the low 30's and I shot the same load in my 284 shehane 57.0 4831sc the same load I shot all summer at 2905 fps. In the low 30's it was 2848 fps.

 

[BartsBullets]

Hogwash. There is no cold column of air inside the barrel.... the air in the barrel is hot due to the temperature of the barrel. And the bullet flying through What atmosphere? The Magneto speed is 3 inches from the end of the barrel. You are correct in that downrange velocities will be reduced due to the denser air

The column of air inside the barrel is hot summer or winter. Keeping your Barrel hot ensures the column of air inside the barrel will also be hot, so the air density would be the same inside the barrel. And as far as the bullet flying through the air ....how much affect could cold weather have on 3in of space between the muzzle and my Magneto speed? You are absolutely correct in that the point of impact will be much lower due to the denser air, but velocity , and the group shape and size will remain constant. Interior ballistics will be identical.... exterior ballistics will be different.

Tod,

Bullshido!

Load up some R15 or Varget in the house go out and shoot it in 15 degree weather. Then shoot in 70 degree weather. The velocities will be different. Keep them in a cooler, shove them under your truck heater. It won't matter. I think there are some powders that are less moody with temperature changes. But the two I just mentioned aren't.

Bart

 

[BartsBullets]

I shot last week and the temp was in the low 30's and I shot the same load in my 284 shehane 57.0 4831sc the same load I shot all summer at 2905 fps. In the low 30's it was 2848 fps.

BINGO!!!!

 

[4xforfun]

Hogwash. There is no cold column of air inside the barrel.... the air in the barrel is hot due to the temperature of the barrel. And the bullet flying through What atmosphere? The Magneto speed is 3 inches from the end of the barrel. You are correct in that downrange velocities will be reduced due to the denser air

The column of air inside the barrel is hot summer or winter. Keeping your Barrel hot ensures the column of air inside the barrel will also be hot, so the air density would be the same inside the barrel. And as far as the bullet flying through the air ....how much affect could cold weather have on 3in of space between the muzzle and my Magneto speed? You are absolutely correct in that the point of impact will be much lower due to the denser air, but velocity , and the group shape and size will remain constant. Interior ballistics will be identical.... exterior ballistics will be different.

Tod,

Bullshido!

Load up some R15 or Varget in the house go out and shoot it in 15 degree weather. Then shoot in 70 degree weather. The velocities will be different. Keep them in a cooler, shove them under your truck heater. It won't matter. I think there are some powders that are less moody with temperature changes. But the two I just mentioned aren't.

Bart

But you are saying that you are shooting INDOORS!

 

[BartsBullets]

But you are saying that you are shooting INDOORS!

Todd

Shoot it indoors or outdoors. It will do the same thing!