BobT
Gold $$ Contributor
I know this thread is an older one but I have both the 6x45 and the 6mm Mongoose. The Mongoose out performs the 6x45 and it's not quite as potent as the 6 TCU. My mongoose dies are in fact cut down (.020 I think) TCU dies. The Mongoose is proprietary to Mad Dog Weapons Systems and was designed to function through a standard AR 15 using .223/5.56 bolts and magazines, the TCU is just a little too long for optimum performance in the AR. If barreling a bolt gun there is nothing to gain over the TCU but you can get a barrel made if you desire. For more information on the Mongoose visit the MDWS forum there is extensive data and other information available. For what it's worth I shoot my 6x45 more than the Mongoose but it's because the 6x45 is chambered in an XP100 pistol. In short, both are outstanding rounds IMHO and I like one as well as the other.
