There are so many different 'slugs' today, along with so many different handloading choices, it's possible you can get the barrels to shoot just fine, by simply shortening them ot 24" or 26" and mounting iron sights.

The 'doll's head on Spanish shotguns does little to increase saftey of the action. The 'bite's prevent the barrels ovement forward and the doll's head does not prevent the barrels from opening as is shape promotes that. According to Greener, the doll's head was merely a hollow marketing maneuver - sounds logical to me.

With cup-wads ie:the bases or interior bottoms of steel shot wads will hold undersized projectiles centred in the bore upon discharge. I've used this to advantage with lighter round ball loads, ie: 14 bore balls in a 12 bore, with excellent accuracy. This keeps the balls from leading the bores and the wads seal the bore and keep the ball centred.

My double 12 would hold on a 10" steel plate at 100 meters, offhand, alternately firing rights and lefts. I'd mounted a scope for testing ammo and it surely helped if my offhand shooting at that plate. It shot the same without the scope attacked. This was probably due to the low speed of the ammo I was using - 1,500fps max. with black power and smokeless powder.