Peterson Brass Belted Mag Basic Unprimed Box of 50

Nice work. Def gave me the itch to try it and glad I did.

Not near my notes right now but I got 16 or 17x firings before I noticed a hairline split starting to form above the belt so I stopped. This was pushing the 183 SMK above 3100fps with h1000. Primer pocket was still tight. I couldn't believe it.

The 6.5x300 Wby is probably the way to go. Could also neck down 300 Wby. I ended up finding a 375 Wby die and that is the way to go in my opinion. It has much less body taper than the 375 H&H which reduces the amount the brass shrinks in length that first shot. My final process was 416 to 375 Wby, anneal, 8mm Rem, 7 STW, anneal, trim/chamfer/debur, load and shoot.

Anybody that wants to use the dies to make their own let me know.
You have gotten a lot of firing from those cases. That great. I don't how much you are bumping the shoulder back on those cases. I found a long time ago with my 308 NM that just using a neck sizing die stop the case separation at the base. I resizing 300WM brass into the 308 NM brass. Fire-form them. I would lose the brass in 3 firing or so doing FL sizing. Change to using a 300WM neck sizing die. My problem with case separation stop in there tracks. Note: that 308NM is shorter to the shoulder than the 300WM. So I figure could use it after fire-forming the brass. It fit my chamber after that. The 300WM neck sizing die only sizes about 3/4 of the neck for the 308NM. I was working on grouping use a neck sizing die. Couldn't get a 308NM neck sizing die.So I changed it to 300WM neck sizing die. By accident I stumable on to having case separation. I run my 308 hot powder loads. So I would lose then in about 10 to 12 firing do to primer pockets. I have 3 338WM rifles. I am going to use those staight wall case to size them to 338WM cases. I like your imput on using 375Wby dies.
Now if I could convert something like Peterson brass into 220 Swift. I would have it made. 😁