I saw your request for a 16 gauge sidelock. As for sidelocks, I have a highest quality Lajot, a gunmaker of distinction. It has 28" barrels , invisible welded seam sleeved by John Foster [and gunman on the DGS board]. $3700 plus freight
Not sidelocks, but guns of highest [best] quality are--
Charles Daly, 16 ga, highest engraving coverage, boxlock. Fluid steel. $4000 plus postage
Hoffman Arms, 20 ga., boxlock [England sourced] , highest quality engraving by Rudolph Kornbrath, top condition, cast on for a lefty. Gold animals. The best found. 1924 manufacture. $7200 plus shipping.
Greener, Monarch Imperial , 16 gauge, [70 Guinea gun] , boxlock. Fully engraved with gold crown and scepter indicating the Imperial Grade, Whitworth barrels. $7900 plus shipping
If any of these sound interesting , email me at darylh1942@gmail.com.
Best, Daryl Hallquist