I was thinking about having my REMINGTON 700 SENDERO 7MM MAG Rebarreled for the 257 STW but was told by a member of another forum to take a look at the line of Allen Mag Cartridges on this forum before i rebarreled the REMINGTON 700. What are the Allen Mag Cartridges and where can i get more information on them??? I have done a few searches but no luck so far. Please help!!!