Home Forums Reloading Big Game Rifles Case neck thickness, inside/outside trimming?

My gunsmith recently finished my 6.5-.300 WSM. It's a Win. Mod. 70 Classic S/A, S/S. It wears a 27" Pac-Nor Fluted S/S barrel nestled in a McMillan A2 stock.

I had loaded up one test round so the gunsmith could test fire it. Much to my surprise said test load blew the primer out. Obviously way over pressure. I had used .270 WSM data then reduced 5% plus an additional grain just to be safe. At first we thought maybe my load wasn't conservative enough, then we thought maybe we were just dealing with a very tight chamber/neck. For the heck of it the gunsmith measured the outside and inside diameters of the fired case. Headspace, btw, was perfect. Here are some dimensions:

This from a necked down .270 WSM case.

Outside neck dia. - .300
Inside neck dia. - .262
Difference - .038

For comparison- .30-8mm fired case

Outside dia. - .340
Inside dia. - .309
Difference - .031

The fired 6.5 WSM case inside diameter was .262 and therefore would not accept a bullet. Should I get a neck turner and inside neck turn my cases .003"? Looking for a little guidance as I've never needed to neck turn anything before. Good luck, Troy

Troy,
Do a chamber cast on your rifle. This will allow you to determine the EXACT neck dimension for you rifle. You can then outside turn the necks on your brass for .0015" clearance all the way around (or more or less depending on what you want).
John

Ditto on the chamber cast.......and I don't know the whole story BUT I would worry about a "gunsmith"? that didn't do the chamber job that would fire a shell in the chamber or if they did the chamber job they didn't check for neck clearance on the loaded round OR didn't do a chamber cast without you having to ask what the "gunsmith" should do.........and to solve the "problem" get a outside neck turner...hand held or one of the mini-case trimmer type lathe versions...FOrster....Hornady has a new hand held one but I haven't seen a "in person" one.......you might also check a few different brands of brass as some lines do vary a lot in the case wall thickness......HTH..good luck and good shooting!!

I wasn't there when he fired it but there was nothing to indicate a problem with the chamber. The loaded round chambered fine. It was when we measured the inside diameter of the fired case that indicated a tight neck or thick brass. Thanks for the guidance fellas. Good luck, Troy