Brass won't chamber

Potashminer said:
Some time ago I had bought previously fired Rem 7mm Mag brass from CGN - managed to pick out 85 or so Remington brand. I was able to reform and trim to make into 7x61 S&H brass. Not a one would chamber into the Schultz and Larsen rifle - jiffy marker showed they were hanging up about last 1/16" or so right in front of the belt - had been Full Length sized, twice, with the Herter's brand 7x61 dies that I had. Pulled out other dies to try to come up with some solution - those 7x61 brass just plunked right in to the belt on my RCBS 338 Win Mag die. But stopped a good 1/2" proud in my RCBS 458 Win Mag die. So, I ran those brass through a third time - this time into that 458 Win Mag die - it was "tighter" just in front of the belt - at least enough that every single brass would now chamber, whereas none would before.
I went ahead and bought the Larry Willis die - read instructions and can not find Imperial wax around here, so bought a tube on Extreme Pressure (EP) grease from NAPA store and a can of acetone to clean up. Still sitting here, not yet used. Was able to come into some proper Norma brand 7x61 ammo and brass and an RCBS sizing die set that have given me no further grief. When I want to get to it, I have about 150 previously fired Weatherby brand 300 Weatherby brass that will not go into my M1917's chamber - so running that batch through the Larry Willis die will pay for that die, when I do that. I suspect that I would get the same result running them through my "tight" 458 Win Mag die...
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Thanks for that info. This is starting to make sense know. I was starting to feel inadequate:(
 
What I did was make a poor man's collet die.
I have access to a lathe. Took a RCBS small base 300 win mag die. Trimmed the bottom of the die off. Taking the belt and about .050 extra. Cut the die off at the beginning of the shoulder.

The dies are tapered. Starting at .511 and ending at .475 at the shoulder (for the 300). By removing the belt and a bit extra it moves the case further into the taper. Make sure you have the slightest chamfer. Then by removing the top, the case can stick out making it a body die. Just run the case into the die untill the belt makes contact and done. Pushes it to about .506. The 300 win is a different taper than the 7mm...

I have done the same with a small base 7mm rem die. It has a different taper .511 to .490. This one I have trimmed it real short on top. Just enough to fit the press with the lock ring.

With one or the other I can get the case back into workable order.

Trying to locate a 480 Ruger carbide for a project next. As it looks like it might work. I could probably modify it. Carbide would be nice.
 
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I should also add that doing this is also possible using regular dies. I had a bunch of Lee RGB dies. Cut the top off and then removed the belt and about .080-.100 untill I got the desired squeeze. I just found that small base dies can sometimes be found for a song.
 
...or just take a bit off the shell holder to send the case further into the die? I have had to do this in the past with different rifle/calibre scenarios. Shell holders are cheap and the press can be set to stop at the original length if required in future.
 
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woodlotowner said:
...or just take a bit off the shell holder to send the case further into the die? I have had to do this in the past with different rifle/calibre scenarios. Shell holders are cheap and the press can be set to stop at the original length if required in future.
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I have tried that. The issue is that the case stops in the die at the end of the belt groove. Need to modify a die to get the case in further into the taper.
 
I have a 300 win mag that does this and I had eventually figured out. I still don’t know what is the root cause? A tight chamber, too deep of chamber for the shoulder?

I eventually got a small base 300 win mag die and only bumped the case back far enough to where the hand loads would rechamber.

If I full length resized, the brass would be a couple thousands too thick just above the belt and not chamber properly.
 
Look at the SAAMI cartridge and chamber drawing below, the manufacturing tolerances for the case diameter just above the belt is + or - .008, and the chamber diameter can vary .002 in diameter.

So if you have a skinny case and a fat chamber the case can bulge above the belt and the resizing die does not touch this area. And some brands of brass are thicker above the belt and may not have this problem.

Another problem is the case can vary .008 from its base to the top of the belt and the rifles headspace can vary .007. And this why you want the cases to headspace of their shoulder and not the belt to help prevent case head separations.

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