You need an "E" box for a .300WM???? Those are normally for the full-length magnums ala .300HH or 7mm STW..
The (E) Magazine (DBM) "As Pictured" is what came with the .300 Win. Mag. I currently possess "Purchased New". However, MidWest GunWorks shows an (EC) for a .300 Win. Mag (CRF). What do I need, (E) as originally with the .300 Win. Mag. or (EC)? Thank you for the reply but I find the response somewhat confusing. Again, the (E) designation from MudWest GunWorks states for (Push Feed) 'only'.