I was and am too cheap and broke to buy a set of 7mm Mashburn dies, but my rifle will eat up and fire just fine 300 WinMag brass run through a 7mm STW FL sizing die. From that first form down, I merely run that same die back a few turns and neck size only.
The 7mm RemMag to 7mm Mashburn Super conversion is SO easy, and makes SO much sense, I hope and think that we will be seeing this done to more and more vanilla 7 Mags.
If anyone has any experience or data for the 7 Mashy or the nearly identical 7 practical and 7mm/300 WinMag with 120-140gr bullets pushed fast, I would love to see it. H4831 got my Barnes 120's to 3700fps but I have done precious little testing or development other than toss together that quick load for a soon upon me deer season and call it good enough. My hope is to get the higher BC 139-140's out the snout at 3500fps, (from my 26 inch octagon barrel) safely and with good primer pocket life.
Last edited by safariman; 12/02/14. Reason: left some words out!
