Belted Magnum Resizing

[Rmeju]

I have a few questions about belted magnum resizing for all you High-Roaders.

I started another thread asking some questions about neck sizing for a 7mm RM bolt rifle, and I had some more questions re: "headspacing," case separations, and sizing.

I see that there is an issue with belted magnums separating, and the proper way to resize them. I bought a Lee collet sizer, and it sounds like that will work for awhile, but eventually I'm going to need to FL resize so that the brass will fit in the chamber again. (Am I right so far?)

I understood from the above thread that FL sizing will push too much material down near the belt, and/or push the belt back such that the case is unsupported, and (may) therefore fail by separating. I'm not clear on which problem FL sizing is causing, or even that it's not what I should do, since some people said FL sizing is the best way to resize a belted magnum...

In the thread, some said the case headspaces on the belt, others said the shoulder. Which is correct? Does it matter as long as it measures out in the headspace gauge?

Some of this advice sounds conflicting, although I'm probably just not understanding it. I want to do this the right way the first time, so any help getting me straightened out on these points would be greatly appreciated!

Thanks!

 

[brickeyee]

Ignore the belt for reloading and use the shoulder.

 

[nastynatesfish]

Ya shoot your first go round and neck size till it gets tight. If your having case head separation you've got .005 or more headspace or your loading way to hot. I've got 7 mag brass that I've been loading since 2008. I use a collet but you can also set you FL die to just barely bump your shoulder back to ease up chambering.
The belted mags headspace off the belt for the first firing after that it's your chamber, do what you want with it.

 

[nastynatesfish]

Your die isn't going to push material to the belt of the case lol. If its seperating it's from all the fl sizing and the case stretching to fill your chamber. Every time you fl size you mash the case and it wants to fire form to your chamber. iTunes how to bump shoulders back with a fl die. That's the way to go when it's time for a fl size.

 

[rg1]

Only belted magnum I load for is a 300 Weatherby. My die will push the shoulder back too far with firm contact with a shellholder. My cases when I first started loading showed stretch marks and could cause case separations at only 3-4 loadings. Learned quickly to have the shoulder of a belted magnum case headspace off the shoulder and not just the belt. Some case headspace gauge is a must have in my opinion for adjusting your sizing die to only push the shoulder back a measured amount. Measure a fired case and adjust your sizing die to only push the shoulder back 2-3 thousandths or you will only get 3-4 loadings before you could get a separation. Even then do the bent wire feeler method on your belted cases to feel for possible case stretching.
I like Hornady's Headspace Gauge set because it can measure most rifle calibers and is inexpensive.

 

[Clark]

I just finished processing some 7mmRM brass yesterday.
Inside the boxes I have a note:
7mm Remington Magnum
This brass was once fired in FL in pressure test barrel
$45 delivered for 260 pieces 4-18-2013
[individual source]
I decapped.
I stainless steel media tumbled.
I lubed with Redding imperial die wax.
I sized with a Bonanza FL die with .307" honed out neck on Forster's Hardinge collet lathe.
I moved the shoulder back far enough for Ruger #1, the tightest rifle I have. My other rifles are shorter headpace to the belt, but the Ruger factory reamer was shorter to the shoulder.
I partial inserted Lee Collet neck die mandrel.
I chamfered the case mouth with RCBS 20 degree chamfer.
I cleaned out brass bits with Q tip
I primed with Bonanza primer with Rem No. 9 1/2 large rifle primers

Using a Sinclair concentricity gauge and a pin gauge for a bullet, I could tell that it was best to just be changing the inside diameter from .004" interference with the .277" bullet to .002" after the Lee Collet neck die mandrel has been in there is best done by just barely entering the mandrel in the mouth, and not going all the way to have the mandrel go through the flash hole.

 

[Walkalong]

In the thread, some said the case headspaces on the belt, others said the shoulder. Which is correct? Does it matter as long as it measures out in the headspace gauge?

Ignore the belt for reloading and use the shoulder.

That. Use the shoulder to regulate headspace.

 

[adobewalls]

I have set of 50 cases I have been reloading for nearly ten years, so I probably have 10 to 15 loadings on that brass.

I only neck size and I shoot a moderate load (61.5 of IMR 4131 and a 150 gr. nosler.)

The brass still chambers easily, the load is very accurate and just this last February it was responsible for putting a South Texas Doe at a 175 yards away into the freezer. She was dead before the sound of the rifle going off got to her. My son also draws from those loads for his rifle and it put down a hog at just under 400 yards, hitting it just behind the ear and down 2 inches.

I have had the special collet die to resize the base just above the belt for about 8 or 9 years but I have never needed it.

 

[gamestalker]

New belted brass head spaces on the belt. After the first firing use the shoulder as your head space on that end of the cartridge. I have tried two different methods of resizing my 7 mag brass, full time FL, and necking with intermediate FL sizing when things get too snug. I've now settled on necking with FL when shoulders need bumping. But you have to be cautious about how far down you set the FL die, so as to not over do it or you'll experience premature separations. I don't use any gauges, but instead I just make very small adjustments to the FL die, until I'm chambering without maxing out at the shoulder. Once I've found that adjustment, I measure my die off the top to the lock ring, write it down in my log book for future FL sizing, life's good.

I average about a dozen runs off my belted brass, and just slightly more on standard bottle neck brass.

However, there are colet dies that are out there that are supposed to be the ticket to hassle free belted resizing, and extend brass life dramatically, so I'm told.

GS