From the link provided by EOD ( viewtopic.php?f=8&t=18304)-
On page 29 of this presentation the .264 is pictured (a portion of the page shown below), including an all brass case cartridge and a brass base/polymer case cartridge:
On page 39 of this presentation is a listing of weight reduction for ammunition with a polymer case vs. brass case ammunition in a "combat load" situation and the .264 polymer case cartridge is one of several cartridges listed.
The same or similar image of the .264 cartridges is briefly mentioned here: thefirearmblog.com/blog/2015 ... d-264-usa/
So is there any further information on this cartridge?
Is the polymer case cartridge being produced by MAC, LLC for certain (MAC is discussed here: viewtopic.php?f=8&t=18213&hilit=MAC)?
If not MAC, LLC then who is producing the polymer case ammunition?