Bow View,
The other way you could use a five shot gun would be to load 4 and leave one empty. Then, either load the fifth one before shooting (which would be easiest) or shoot four, then reload one.
The one gun with the dull finish could be polished to look like it was polished nickel.
Then, you'd be in the position that St. George warned about. Competition would ruin those antiques quickly.
That "Dura-Coated" one sure looks good, 'tho - it's in nice shape under the re-finish.