Okay, let me give y'all some background.
You know my great shooting 45-120 barrel...  Well, it was snuggled into a bank vault tight fitting SB2 receiver.  Never being one to leave well enough alone, I figured I'd give that rec'r back to it's original 45-70 barrel and get a nice case colored receiver for the 120.  (Yes, I useta like my wimmins dressed up real purdy to!   

 )
I finally ended up buying a whole 38-55 TC here on the classifieds, figuring I'd keep the action and put the wood on that old 45-70.  I would then sell the 38-55 barrel to recoup some of my expenses.  So far so good.  BUT the best laid plans of mice and men and all that...  

I had already bought 50 pieces of 38-55 brass... but 
only because Midway had them on clearance.  I mean...  really!   you never know...  

I sluged the bore and it came out an even .380.   Cast bullets only...  
  I was still debating the disposition of the barrel when I went to a local gunshop.  And there I found, hidden away, a used but like new set of RCBS 38-55 dies, very cheap!  I was done for and in the 38-55 business.   

Worried about the large bore vs. tight chamber problem, I assembled a dummy round last night using a cast FNGC bullet sized .380.  No way it would chamber.  The round stopped a good 3/8
ths of an inch short of seating to the rim.
I'm going to go back and reread what posts I can find on this issue, but I am not a happy camper!   

  I hope it is as easy a fix as rereaming the chamber...