[flashhole]

Your options are:

1) As already stated, take some material off the bottom of the die.

2) Take some material off the top of the shell holder. I've done this a lot. Technique is to drag it across emery paper. Takes a while but it works. If you have more than one shell holder for that case you might measure them and swap them out to see if it makes a difference. I have shell holders dedicated to certain guns with tight chambers.

3) Put a shim under the brass inside the shell holder. I've used aluminum foil and it works well.

All three methods will net the same result ... you bump the shoulder back just a bit more and rounds will chamber.

Also, I suggest you anneal the brass.