around the turn of the last century OWS had have a lot of 14 gauge greener police gun brass. it was 3 dollar for a case then, a good price for 14 ga brass and I take a box from them. the last 50 I had where gone to a collector to fire a very old(around 1860 iirc)Needham double gun. it was nessesary to thin the rim a little bit.
the 12 ga Lee forster slug mould was casting a .705 slug that fits inside the 14 ga perfect.