Like AtlLaw said, I thought it was handled. xhare describrd it pretty well. And BTW, 300 mag has nothing to do with it, it is belted mag in general & chambers can and often are a little slopy from the factory in std. &
mag calibers as well, the difference is where the stretch takes place in the case of the Belted mag, in front of the belt.
But I have
NEVER owned a factory belted mag that gave me a problem with factory ammo, I could just shoot it & reload. But if you full length resize every time the case life can suffer. It is best to gve the shoulder a minor bump (experiment with what you chamber needs), thus headspacing on the shoulder. I neck size & after 2-3 firings doing so I will give the minor bump if needed. Nothing complicated at all, just headspace on the shoulder & don't overwork the case. If you do this, it is not that much different than other cases, just leave the belt out of the equation.
The above will serve you fine & you can read more in reloading manuals that explain it better than this, but if you want to get complicated & look at more detailed options, I will give you 2.
1. Special die to size ahead of the belt. One die will do all H&H dia. cases.
www.larrywillis.com Scroll down to Belted Magnum Collet Resizing Die.
2. Special method which will also help to make loads very accurate, this is with your new brass only.
http://www.shootingtimes.com/ammunition?ST_beltedcasebull_201007/index.html Click on page 2 for the article, belted case blues.
The last 2 are for serious volume shooters & those who like to tinker, the first for the more typical magnum shooter/hunter. Merely giving someone the time, or showing them how to build a watch, your choice.
