The 6br is the only one claimed different. Didnt need a different chamber but when you formed a dasher it blew out longer. No need in trying to seek any out especially in any other caliber. Dont pay extra for the box thats for sureONLY IN 220 RUSSIAN i think, or maybe 6br
one is like gold in the gold box if you have a chamber cut on the old brass
+1The 6br is the only one claimed different. Didnt need a different chamber but when you formed a dasher it blew out longer. No need in trying to seek any out especially in any other caliber. Dont pay extra for the box thats for sure