I have a beretta postwar hammergun in f/f [not for sale],
which behaves absolutely sick at 16yds,
["sick" meaning devilishly good],and at normal field dimensions
28"bbl,cheekpiece,factory plate,etc.
Trap was a live pigeon sport,so dont dismiss any live pigeon gun like the bernardelli las palomas,or bernardelli hammerguns.
OOPs sorry,your on a budget,hmmm,look into a husqvarna hammergun,they can be had for little,and little used,and original f/f chokes.You wont have high patterns with converted field guns unless you jack up the comb with a stick on comb riser of some sort they sell.