Belted cartridge - When head clearance is adjusted off the shoulder, with only 1 or 2 thousands bump, the area in front of the belt becomes unsupported in the rifle chamber. This unsupported area may bulge after a few firing, if using full power loads. SAAMI drawing A maximum chamber headspace at .227" when compared to a minimum cartridge belt head clearance (.220" -.008") or .212" = .015" slop. Hopefully, your chamber is tighter.

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If you EVER need a collet-type lower body sizing die in order for your loads to chamber (regardless of whether the case is rimless, rimmed, rebated, semi-rimmed, or belted) then your pressures are unsustainable. You'll be using Scotch tape to keep your primers in at that point.

I have reloaded the same Winchester brass in my 7mm Rem mag up to 14 times. Using the same load. The collet die sizes where the FL die, especially when PFL sizing cannot. Right at the belt, not the belt, just above it for a few thousandths.

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Belted magnum cartridges have been around for over 50 years, and most shooters that reload them are familiar with the case bulge problem that occurs "just above" the belt. This usually happens after just 2 or 3 firings - wasting perfectly good cases. Many shooters have discovered this problem when they find their handloads begin to stick in their chamber, or when they no longer chamber at all.

I dislike belted magnums, have had rim lock, in the magazine, with my M70 375 H&H, and this is just another good reason to dislike the belted magnum case design.

Another good reason is that the shoulder to base distance is not controlled. The cartridge headspaces off the belt and it is easy, and common, to push the shoulder back too much. I had to buy the special Wilson case gage, pictured here:

Extending Cartridge Case Life

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

Because it required special gages to set up my dies to bump the shoulder back so that I don't have resistance closing. And once the die is set up for one rifle, it won't work belted magnum brass fired in another rifle, because the shoulder to base distance is not controlled.

As someone who wants perfect function, I don't neck size, and I don't want crush fit cases. I have shot out enough barrels in high powder competition to know that cases that are an interference fit in, are eventually going to be an interference fit out. It may not bother a hunter to have to find a cleaning rod to knock the case out of the chamber, but for me, breaking position, losing track of the wind, and eating up my allotted shooting time because the case won't come out, is reason enough to full length resize.

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Originally posted by 243winxb:
Belted cartridge - When head clearance is adjusted off the shoulder, with only 1 or 2 thousands bump, the area in front of the belt becomes unsupported in the rifle chamber. This unsupported area may bulge after a few firing, if using full power loads. SAAMI drawing A maximum chamber headspace at .227" when compared to a minimum cartridge belt head clearance (.220" -.008") or .212" = .015" slop. Hopefully, your chamber is tighter.

In my case...not LT's...there is no shoulder as I was talking about a .458 WM.

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243winxb

243winxb,
That link to Brownel about headspacing was a great help.
Thanks,