Why?

At least ours work as intended, winter or not.

It is more a case of the problems with freezing and thawing of propellants. Best case scenario they work but not as well, worst case they either don't work or work "too well". :o

Unless one is careful when they freeze powder or powder-like propellants, it is easy to get condensation from the atmosphere this, when thawed can adversely affect propellants.

The problem is that mortars are designed in such a way that to operate them, the projectile and propellant bags are held above the opening of the tube, then dropped. Anyone who has fired a mortar knows that it does have to be lined up kinda carefully or one risks hanging the round - bad thing.

This lining up is pretty easy for a human, but rather hard for a mechanism. This is why automated mortars don't operate like human operated mortars. In order to use ice, some sort of holding frame would need to be constructed to hold the round, aligned with the tube, in such a way that it is released evenly.

Ice does not melt evenly. The only way I could see this working is if the round were held in some sort of clamp which is somehow released due to ice melting.

Way too complicated. They key to improvised munitions is keep it simple. Simple works, complicated don't.

If I wanted to remotely fire a mortar, I would construct a ramp like cradle and suspend the round from a string. Then choose one of the thousand ways to cause a string to break and Bobs your Uncle.

What would be critical temperature for performance of mortar shell? I'm asking because Finnish Army have order to defend country no matter if temp is +40 or -40 degrees celsius and we use mortars, a lot... mortar here... mortar there... few more over there...

I think the accuracy may vary much between those condition.
Its not big issue for mortars.

Possable your shells are designed for those conditions.

What I was getting at is that some explosives are two stage. There is a large amount of a standard stable high explosive or non explosive filler and a smaller amount of a more unstable high explosive. Like Dynamite, its Nitroglycerine and an absorbent mixture that prevents it from being unstable. If you freeze it the Nitro can be forced out of the Dynamite and become again highly unstable.

That is the worst case scenario, true Dynamite isn't used by the military anymore but TNT is and for example RDX can leached out of TNT or C4 if its frozen, this could result in a bomb that doesn't explode efficiently and "wastes" its energetic material.

If you had a Soviet 160MM mortar I think you could rig it for remote fire a lot easier. Its a "break action" mortar, you don't drop the round down the tube.

Down side is: its one big mofo!

Don't forget: it takes balls to fire a projectile:

http://img831.imageshack.us/img831/6268/launchi.jpg

I thought it a way to camel race...
http://t1.gstatic.com/images?q=tbn:A...xG9HvTB4dN_EyM

I love that there's a tree stump in the desert. :rotfl2: