• You must be a Supporting Member to create a listing in the Long Range Hunting Marketplace. To read all the rules, click here.

    We offer multiple options to become a Supporting Member here.

Peterson 7mm Remington Mag "Long" brass in stock @ Grafs.com

martinakl

Well-Known Member
Joined
Nov 27, 2013
Messages
2,484
Location
SW IDAHO, 83713
I stumbled across this today.


1675042879338.png
 
I don't know how much "longer" it is if any. But the "long" it is designed to be head spaced off the shoulder instead of the belt.

So the overall length may not be any longer at all.
 
Last edited:
the "long" designation being Headspaced off the shoulder isn't entirely true. The 300 win brass vs chamber dimensions aren't the same. I believe the belt to shoulder length is about .01-.015 different so a fired piece of brass has to expand and form into the chamber. All this expansion can cause early case head separation. Peterson's attempt to resolve the issue is the make brass that is longer andmatches the chamber specs. It still headspace's off the belt and works in factory chambers
I dont know if that is an issue with the 7 rem as well. Must be if they are making "long" brass for it.
 
If I'm mistaken I apologize, as I have not looked at or nor examined the drawings.

I was trying the reduce this quote from the Grafs.com product page on Peterson's 300WM Long brass.
"Peterson Cartridge Co. of Pittsburgh, PA announced it is producing .300 Win Mag casings in two versions. Peterson makes the traditional SAAMI spec'd version that headspaces off the belt. But it also makes a version that headspaces off the shoulder. Peterson calls that version the .300 Win Mag- Long."
 
I've got some of the 7RM Long brass ordered. The 300WM Long brass I have is top notch. Out of the box it was.002 short to the shoulder of the chamber on my rifle. Most factory ammo is.019 to .022 short in my 7RM. I took some virgin Winchester brass and expanded the necks to.308 and then sized them in my full length die screwed out about 3/8 turn and made them a crush fit and after 3 firings they still don't need trimming. Fire formed in this way, it eliminates the stretch in the body of the case.
 
I stumbled across this today.


View attachment 433562
Thanks for the heads-up! I got a box of 50 7mm RM on order.
 
Thanks for the heads-up! I got a box of 50 7mm RM on order.
Nice. They only had the 250 count option when I posted. Smaller qualities is a nice option.

 
I believe I read it is .011" longer base to
Shoulder datum.
.011 longer than what ? From what I've seen the base to datum length is all over the place depending on brand or even lot numbers. I don't know why ammo, brass and gun mfgs can't get closer on the specs for belted magnums. They do it all the time on the standard cartridges.
 
Top