Questions on loading belted magnums

[Southern Raider]

I am considering a purchased of a belted magnum rifle (possibly 458 Win Mag) and had questions on the reloading of the rounds. Some literature makes a claim that the case will swell just above the belt, even with full length resizing, and render the case useless after 2-3 firings. If I did make this purchase, I would probably keep the loads warm but not hot. Will I run into this?

Is neck sizing an option for belted magnums?

Would a Dillon 550B be suitable for loading these rounds? I'm not after volume; it just the only press that I have...

 

[Walkalong]

Sizing the belted magnums to headspace off the shoulder like other rifle rounds will vastly improve case life vs full length resizing them by screwing the sizer die all the way down and relying on the belt for headspacing.

I don't know if swelling with belted mag cases is any worse than other rifle rounds, but maybe someone will chime in with some experience here.

Sure, you can neck size for belted rounds with the same limitations as there are for other rifle rounds.

 

[zxcvbob]

There's a special collet die that you can buy to resize the cases right to the belt. I'm not sure who makes it, but it shouldn't be too hard to search for.

 

[benchgrinder]

The company that makes the special collet die is 'Innovative Technologies'. On their website they claim that they're sold out, but are accepting emails to start a want list. Once they get enough demand they'll make another batch of them. I'm looking for one of those dies as well, specifically for 300 Win Mag.

 

[North Country]

Hello- I bought one of those dies a couple of years ago Unfortunately I haven't had a chance to use it yet (new brass and haven't shot it up yet) anyway the same die can be used for almost all the belted magnums 300 win-7mm mag - 338 win ect. it also can be used as a check or snap die to check your loaded ammo and a loaded case can be inserted in the die and resized to the proper size. all in all kinda neat.

 

[Grumulkin]

I am considering a purchased of a belted magnum rifle (possibly 458 Win Mag) and had questions on the reloading of the rounds. Some literature makes a claim that the case will swell just above the belt, even with full length resizing, and render the case useless after 2-3 firings. If I did make this purchase, I would probably keep the loads warm but not hot. Will I run into this?

I load for several belted magnums including a 458 Lott and have never had this problem. My loads are not downloaded at all but not excessively hot either. I've had very good case life with my 458 Lott.

Is neck sizing an option for belted magnums?

Yes; just don't run the case all the way into the die. Just run it in enough so when the bullet is seated, it's firmly in the case.

Would a Dillon 550B be suitable for loading these rounds? I'm not after volume; it just the only press that I have...

I've never used any type of Dillon press so I don't know. I get by just fine with an RCBS Rock Chucker and a Redding T-7 turret press. As long as there is enough room to get a case and bullet into the press to seat the bullet, it should work fine.

I, by the way, have the Innovative Technologies die and have never had to use it.

 

[dogrunner]

The Dillon will work for belted mag.s, but depending on charge levels you might find yourself having to purchase one of the large capacity powder slides. Other than that the press is more than capable of producing very good ammo.

 

[Slamfire]

Belted magnum chambers are cut based on the belt headspace, not shoulder headspace. So you come along, size the case based on the standard bad advice of "touch the shellholder and give a 1/4 turn", and guess what?, you have pushed the shoulder back some huge distance.

When you size belted magnum cases, it helps to use a Sinclair case headspace gage. You do not want to push the shoulder way too much. This web site is really useful for showing how to use case gages. I recommend looking at the pictures, and it explains the special case gages needed for the belted cartridges.

http://www.realguns.com/Commentary/comar46.htm

 

[Wildfire]

All Are Right.

I agree with all these guys. Belted Mags. were designed to headspace on the belt. But later found that the shoulder was the better way. Without a tool to check the headspace you will be lost.
RCBS makes one and so do other companies. I have all RCBS precision Mics. They work fine. I have found that the marks on the guages do not always work and can be confusing. So I mic the outsides of the guage and come up with my own numbers. Setting the dies by the book will produce way too much headspace. You can use full length dies, just dont go down as far. Only move the shoulder back .001 to .002". This should allow good chambering. But load a few and check it. I do not know of any dies that will get rid of that buldge by the belt. If it comes out OK, it should go back in OK.
The RCBS Mics can get expensive if you get one for each cal. There are others out there that probably work just as good for less. Sounds to me like most of these guys know their stuff and can be trusted. What ever you choose have fun with it. Just for fun check a box of NEW ammo some time. See what their specs are. You will be Shocked and maybe even scared.
Even the premium stuff has the sloopiest specs a reloader has ever seen.
All chambers are different. A guy brought me a rifle recently in .300 win. that could not hit with it. Showed me his Win. Supreme ammo. I checked the headspace and found .017" on some. It shoots 1/2" now.