Saturday, March 29, 2014

Polymer Cased Ammunition? This Sounds lIke A Bad Idea To Me

And here you can see what happened when someone fired some .308 Win. with polymer cases in a rifle with a fluted chamber (like the H&K 91 uses).  Thanks, I will stick with brass, steel, or aluminum.


  1. Never having heard of a "fluted chamber", I googled it and found this:

    Apparently, only 7.62 NATO can be used in a fluted chamber. All .308 Winchester ammo is potentially dangerous.

  2. I got rid of my CETME on account of the fluted chamber and the damage it does to the brass.

    If you don't mind throwing brass away, the CETME or H&K are fine.

  3. Alicbiades
    The problem you note is cased by the dimensional differences between the STANAG 7.62x51 NATO cartridge, and the originally civilian (SAAMI) .308 Winchester cartridge. The major difficulty is the headspacing, which is discussed here:



  4. I purchased some polymer-cased 5.56mm ammo a few years ago. I still have perhaps 100 rounds of it and would be happy to give it away. It caused jams (specifically, failure to extract), I think because the cases tended to expand (more than brass, anyway) and would stay in the chamber.

    A learning experience, as some might say.