There's several potential problems with 'plastic' cartridge casings:Hobot wrote:Why not?Death from the Sea wrote:Now this is interesting... and kinda scary, I am not sure I would want to shoot ammo with a plastic casing to it.XM-8 specs wrote:It will fire all standard 5.56mm NATO ammunition, and, to further decrease the load on the future infantrymen, a new type of 5.56mm ammunition is now being developed. This new ammunition will have composite cases, with brass bases and polymer walls, which will reduce weight of the complete ammunition, while maintaining compatibility with all 5.56mm NATO weapons.
-casings melting
Cartdridge casings heat up, and signifcantly so. That's quite intentional because when the used cartridge is ejected, the heat leaves the gun with it, decreasing the danger of a cookoff and reducing wear on the gun.
A plastic cartridge might potentially melt, causing quite a mess.
-casings breaking on ejection
Depending on the rifle, case ejection can be quite violent. A plastic case could potentially get damaged in the process due to lower durability, leaving parts of it in the chamber or ejection port and causing a jam or worse.
...Okay, that's only two but I can't think of any more ATM.
I'm sure some HAB representative will be along shortly to tell you how wrong I am and what's really the problem (if any) with plastic cartridge cases.