The problem isn't the case. The problem is the bullet

Zastava says the 22-250 mag box is 2 19/64 (2.297) long.
http://www.zastava-arms.co.yu/english/civilni.htm

Cartridges of the World says the 250 Savage cartridge is 2.515 long and the case is 1.912.

That leaves about 0.385 for a bullet.

Check the overall length of the 250 Savage with the bullet you want to use to see if it will fit in the magazine.

Maybe someone with a rifle or action can see how hard it would be to lengthen the magazine.

Bruce