Thread: Velocity Loss From Summer to Winter.

Originally Posted by Scribe

'James' you and 'sneeze' might be clear on why there is a 90fps drop in bullet speed between summer and winter but I am damned if it is clear to me yet.

Its the chemical reaction thing. Powders can react(burn) faster(or slower) depending on temp. Usually hotter means faster but not always due to some retardant coatings etc.
Its like a jar full of drain cleaner and a cup of cold water = clean drain, substitute cold for boiling water and you will have a clean ceiling instead.

For any given day, change the pressure and not the temp and there is a requirement to add or subtract elevation. It may be insignificant but it is there, so it is a variable.

Scribe put simply the ambient temp makes the powder warmer or cooler. Warm powder will burn faster than cold powder creating more pressure which intern creates more velocity.There are plenty of variables involving powder types,double base vs single base, burn rates,etc, I personally think barrel and chamber temp has an impact as well but its not something Iv given a lot of thought to. Some people (including myself) carry their ammo in a pocket close to the skin to try and keep it close to body temp in cold conditions, it helps.

Originally Posted by sneeze

Scribe put simply the ambient temp makes the powder warmer or cooler. Warm powder will burn faster than cold powder creating more pressure which intern creates more velocity.There are plenty of variables involving powder types,double base vs single base, burn rates,etc, I personally think barrel and chamber temp has an impact as well but its not something Iv given a lot of thought to. Some people (including myself) carry their ammo in a pocket close to the skin to try and keep it close to body temp in cold conditions, it helps.

Well there you go now, I know what you were talking about. All the time I was thinking outside the rifle, air density, viscosity, moisture and so on and so on. If you guys go on stretching the ranges onwards and outwards you will have to calculate earths rotation into your figures like they do with the long range artillery. Just kidding.

Thanks for that information.

Originally Posted by Scribe

Well there you go now, I know what you were talking about. All the time I was thinking outside the rifle, air density, viscosity, moisture and so on and so on. If you guys go on stretching the ranges onwards and outwards you will have to calculate earths rotation into your figures like they do with the long range artillery. Just kidding.

Thanks for that information.

They allready do Scribe (I dont cos I cant shoot far enough to warrant it)

Corriolis is a factor that has to be considered in some situations as well Scribe.

Originally Posted by R93

Corriolis is a factor that has to be considered in some situations as well Scribe.

Jesus that to huh.

Originally Posted by Scribe

Jesus that to huh.

Ha Ha, yup it is never ending.

Originally Posted by Scribe

Jesus that to huh.

...and the there's "Spin Drift".....oh, the fun that's to be had. Lucky for most of us there are computer programs to get us in the ballpark first

Originally Posted by R93

Corriolis is a factor that has to be considered in some situations as well Scribe.

Damn you 'R93' I am supposed to be writing a book and all my minds does is go around and around now trying to figure out how Corriolis Effect acts on a projectile in flight.

I understand how it effects rotor blades.

Originally Posted by Scribe

Damn you 'R93' I am supposed to be writing a book and all my minds does is go around and around now trying to figure out how Corriolis Effect acts on a projectile in flight.

I understand how it effects rotor blades.

Sorry Scribe I have never been the reason for writers block before.....cool.
Apart from my spelling of coriolis its effect is not too much at ranges under a 1000. 7mmsaum explains the requirements.
Your one up on me though............I understand how it effects projectiles and weather patterns but not rotor blades. But dont worry as I have the attention span of dried fruit so it wont cause any delays in my day. I have been tormenting a fire ant mound near where someone else is sitting. He's ex group, but a pussy. I am hoping he squeals like a girl when they get really grumpy!

Originally Posted by sneeze

Scribe put simply the ambient temp makes the powder warmer or cooler. Warm powder will burn faster than cold powder creating more pressure which intern creates more velocity.There are plenty of variables involving powder types,double base vs single base, burn rates,etc, I personally think barrel and chamber temp has an impact as well but its not something Iv given a lot of thought to. Some people (including myself) carry their ammo in a pocket close to the skin to try and keep it close to body temp in cold conditions, it helps.

Surely that is what I just said as simply as possible ?

Originally Posted by veitnamcam

Surely that is what I just said as simply as possible ?

Yeah pretty much, I hadnt read your post I just scolled down till I hit scribes question that I asumed was directed at me then hit reply.

Stop the world I want to get off now. Getting too complicated. A least the deer would get a good feed in before I figured out all the equations.

Originally Posted by Scribe

Stop the world I want to get off now. Getting too complicated. A least the deer would get a good feed in before I figured out all the equations.