The Light will only accept and shoot 2 3/4" shells. The Magnum will shoot up to 3" 20ga shells.
If has the magnum cylinder it will.
The sizes of shells it accepts will be stamped on the barrel
In a .44 Magnum revolver, yes. In a semi-automatic .44 Magnum (such as the Desert Eagle), no.
No, they are different sizes.
In general, no. Unless the gun is marked for 3 inch (or even 3 1/2 inch) shells, you should not attempt to fire 3 inch Magnum shells, even if they seem to fit. However, if you have a gun made for 2 3/4 inch shells, and have 2 3/4 inch "magnum" shells, IF your gun is safe to shoot, it should be safe to shoot those "baby" magnums.
sure - clean it afterward
Yes, however, they may not cycle thru, and need to be loaded one at a time. Chamber will need cleaning after shooting the shorter magnum cartridge.
Yes, they are all high brass and considered magnum loads
NO
When were 3inch magnum
Magnums usually shoot faster. Hence the term Magnum