7mm mag resizing problem?

[demented]

 I purchased 400 once fired, resized, trimmed and cleaned Winchester 7mm Remington mag brass.  When checking it in my and another rifle, approx. 30% would not allow the bolt to close, some going so far as locking up the bolt.  I re-ran this brass through my RCBS FL sizing dies, managed to save perhaps 1/3 of those I'd originally found bad.  I don't understand what could be wrong with this brass, getting ready to trash it unless some solution can be found.  I suspect the problem is the length from the shoulder to the base, my dies will not adjust down enough to set the shoulder back further.  I'm no reloading expert, have never seen this before so I have no idea whats going on.

[Wyo. Coyote Hunter]

  D. You might try another die...but once I bought or  someone gave me some .300 win. cases, that I never could get sized down enough to fit in my rifle...at this date, I am not sure what I did with them...but it happened to me also....hopefully someone may have a solution...but I would give another die a try if you can....

[shot1]

It most likely is not the length that is causing your problem it is the web-belt area. The rounds were too high pressure and they stretched the web-belt head area and you can not resize them. I just pitched some cases from my 264 Win mag that were fired with too hot loads when I was testing to find a load. They even were tight fitting going into the shell holder and the primers would almost fall into them. I would bet that the primer pocket is a little loose in yours also. If they were actually once fired cases I have seen some factory ammo that was pretty hot in some rifles. You never know for sure what you are getting used. 

[Grumulkin]

As noted above, the problem probably is inadequate sizing just above and around the belt.  There is a "special" die available to resize that area; I have one and have never had to use it but you might benefit from it.  The brass was probably originally fired in a gun with chamber a bit bigger than that on your gun.

[Smokin Joe]

http://www.larrywillis.com/



However, If you buy a die body from Lee ($13.00) and have a buddy with a lathe, you could turn one out for a hell of a lot less than 89 bucks.

[demented]

 As usual,  I got the answer I needed.  Thanks for the help, I do appreciate it.  I doubt I'll need more brass or a die to fix these, IF they are even worth it.  I only deer hunt with this caliber, perhaps ten rounds fired per year so I have more than my lifetimes supply ready to go.  When I go shoot for fun, its either my bolt action .308, an AR-15 or when I really want to enjoy shooting, my Beretta CX-4 Storm. 

[HL]

I'm a little late, but what you need is a small base sizer. That's what I have to use for my 7mag. Tight chamber, and when I resize brass out of my own rifle, with a standard sizer, they won't chamber.