Neck Sizing 300wsm

[Mitch Rapp]

Just bought a lightly used 700 sps in 300wsm. It came with a ton of extras, including some once fired brass. While messing around with it I discovered that the once fired brass will not fit into the magazine. I could chamber it, but could not get it into the mag. It catches on the railway inside the receiver. Never fired brass did not have a problem, just the fired casings.

I guess that means neck sizing is out unless I want to single load everything. Anyone else ever have this happen? Maybe its a real sloppy chamber?

What will having to full length size my brass every time do to my case life? Its Winchester brass if that matters.

 

[Bart B]

If you use a full length bushing die correctly set in the press to bump fired case shoulders back .002", you may get 20 to 30 reloads per case. Better accuracy than neck only sizing, too.

 

[Mitch Rapp]

The dies I have are RCBS. Not sure if that is the type you mentioned or if I should get another type?

 

[LoneTraveler]

You may have just found the reason someone had this rifle for sale, and you could buy it. My brother bought a out of the box condition used rifle. would not shoot. A bore scope, Oh Crap, and a new barrel it shot great. My first thought is. It is either the chamber is out of spec. and the cases are really swelling, or the magazine rails may be milled out of spec. for the 300 WSM case. Start by measuring the fired case, If it is in spec. Then it is the rails. Good Luck on a solution.

 

[Bart B]

The dies I have are RCBS. Not sure if that is the type you mentioned or if I should get another type?

If those RCBS dies are full length sizing ones, they'll do just fine.

 

[Mitch Rapp]

If those RCBS dies are full length sizing ones, they'll do just fine.

Thanks, thats what I have.


So I need to get calipers and check the once fired brass, as well as the gap between the rails. How do I know what the max size for once fired brass should be in order to know if the chamber is out of spec?

 

[LoneTraveler]

To find chamber and shell specs.
Just go to GOOGLE on your computer. And put in 300 WSM Chamber SAAMI Specs. When it brings up the list, Click on 300 WSM Chamber spec. and it should take you to a page that will give you SAAMI min-max. Shell size and min-max chamber measurements. This will give you the specs to measure and check your fired cases by. Good Luck in this project.

 

[Bart B]

Here's SAAMI's page on 300 WSM chamber and cartridge specs:

http://www.saami.org/PubResources/CC_Drawings/Rifle/300 Winchester Short Magnum.pdf