Peterson Brass Belted Mag Basic Unprimed Box of 50

[Mike Matteson]

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.

 

[josh_127]

Finally got my reloading room halfway setup and started playing with my new Neil Jones custom die...formed cases with his stepdown bushings and so far everything is coming out perfectly. I do have to trim the necks .060 as they're measuring way long but the shoulders are coming out perfectly where I want them. Only gripe I got is the neck thickness is only .0125...my nosler brass is .0155( neck turned to be perfect). My chamber has a .319 neck which means I have .010 neck clearance...a bit much for my liking..I ran the necks long for first firing (2.863 oal) as I know my chamber is 2.871...im hoping on the first firing as the shoulder forms as it should when the neck shrinks back it'll thicken up some...the plan is to trim the fired cases back to 2.855 if they're not there already after firing.

 

[josh_127]

After I get a couple cases formed I'll go into more detail about the process but this Neil Jones die is working perfectly.

 

[josh_127]

Made 10 cases today. First fired with 180 gr mk and a mild charge (65 grains) of data 86 powder...same as accurate 3100...my go to powder for breaking in magnums as the flame temp is so cool but burn rate is close to h1000...just really temp sensitive. Interesting thing happened in that the cases grew longer...like all the way to the end of chamber neck...and the shoulder pushed back .003... scratching my head on this one as its opposite of what I thought would happen. Necks stayed the same thickness...only thing I can think of is my shoulder gauge is reading off a false shoulder from the neck down procedure and I set the shoulders pretty far back instead of .002 from headspace...anyway with the Neil Jones die it took me about 15 minutes to make 10 cases with a amp annealer and my Frankford arsenal case prep center. I'm going to do another fire forming charge to get the shoulders where they need to be then I'm gonna run on these with n570 and Berger 195's and see if it'll go higher than my nosler brass...with nosler brass I was getting 3130fps @81.7 grns...pressure signs @82 grns...28" bartlein barrel. We shall see if the Peterson brass will top it...my goal is to get to 3150+...I know some guys are getting there with 28 nosler and adg brass.

 

[Bghunter338]

You should be able to. I'm able to get 3232 with 190gr atips and 570 with a 28" barrel.

 

[eshorebwhntr]

Is there a reason that your case length is .021 longer than typical spec? Most are 2.850 max. I still can't make sense of your measurements after firing. Seems weird

 

[Bghunter338]

Is there a reason that your case length is .021 longer than typical spec? Most are 2.850 max. I still can't make sense of your measurements after firing. Seems weird

I think it's because you can use these for multiple calibers. Mine did the same thing.

 

[Mike Matteson]

Peterson also builds in belted mag long for 300WM cases. I don't see why they can't size either up or down depending on caliber your rifle is.

 

[eshorebwhntr]

liking..I ran the necks long for first firing (2.863 oal) as I know my chamber is 2.871...im hoping on the first firing as the shoulder forms as it should when the neck shrinks back it'll thicken up some...the plan is to trim the fired cases back to 2.855 if they're not there already after firing.

I was referring to the chamber being 2.871 part

 

[josh_127]

I was referring to the chamber being 2.871 part

My chamber print shows 2.871....my actual to "touch" is 2.873. 2.850 is saami length

 

[josh_127]

This is the reamer print from when it was chambered...I think if most guys ran a camera inside and chambered up a fired brass ...you'd be surprised how much room you got before trimming is needed.

 

[eshorebwhntr]

I'll be honest with you, I can't figure out what the cartridge max length is from that print. But I think the 2.871 is from a datum point to the end of the lead.

I didn't get a reamer print on mine so I'm not sure what it is. Might try to figure out a way to measure it. I'm always trying to optimize my process and I hate trimming brass. Through the 17 firings I got on that Peterson I tested I found that setting the shoulder back .0035-.004 gave me effortless bolt fall. The firing/resizing process gave me between .008-.012 growth in case length. So I started trimming to 2.838 each time thinking my max was 2.850.

This has got me thinking now

 

[josh_127]

I'll be honest with you, I can't figure out what the cartridge max length is from that print. But I think the 2.871 is from a datum point to the end of the lead.

I didn't get a reamer print on mine so I'm not sure what it is. Might try to figure out a way to measure it. I'm always trying to optimize my process and I hate trimming brass. Through the 17 firings I got on that Peterson I tested I found that setting the shoulder back .0035-.004 gave me effortless bolt fall. The firing/resizing process gave me between .008-.012 growth in case length. So I started trimming to 2.838 each time thinking my max was 2.850.

This has got me thinking now

I used to go off saami spec too thinking i was safe....now I run my bore camera down it and chamber up a fired case and actually look at it...I know my stw is touching at the neck at 2.873....and the shoulder head spaces at 2.410...i bump my shoulders to 2.408 and my brass only stretches the neck .002 or so every firing...I got 7 shots on some of my nosler brass and the primer pockets are now too loose...I had to neck turn the brass too... Peterson brass is so much better I'm going to make this work and see what I can get out of it...in my 300 win I was able to run it 80 fps faster and much better groups than Hornady or Winchester brass with no pressure signs on brass.

 

[Murtfree]

I gave the Peterson Basic Belted Magnum brass a second chance after seeing this thread. I attempted it about 2 years ago to make 375 Ackley Brass but the necks crinkled; the 416 Rem Mag die fixed that.
From left to right is an unsized Basic case, .416 Rem Mag, .375 Ackley, 8mm Rem Mag and 7 STW. The two on the far right folded when I annealed between the .375 Ackley and 8mm Rem Mag. Annealing seems to make the shoulders too soft to withstand the pressure of neck sizing to this degree