Ken,

If I've grasped the project so far, you have in mind offering an optimus quality XX action and set of 20 gauge barrels in the white.

You are considering an option for an addition pair of 16 gauge barrels.

Some are interested in a set of 20 gauge chokerifled (Paradox) barrels.

Others would have an extra set of barrels be in 12 gauge.

Some have argued for your supplying a somewhat inlet blank. But, of what quality of wood and do you want to get into hassles over which side of the wood was not up to snuff and why isn't the grain in the wrist straight enough and I want straight rather than pistol grip or Prince of Wales.

I'd stick with action and barrels. Let the barrel maker price extra sets with the extra set price a function of numbers ordered. I imagine you will get a quote that, say, 1-25 would cost so much each; more than 25 to 50 would be so much each, etc. At a certain period of time and with deposits in hand you can, with more confidence let us know what the exact cost of an extra set would be. I can see some wanting two pair of 20 gauge barrels with different chokes, for example; or even two sets of 12 gauge barrels on the same logic (assuming the XX geometry permits fitting 12 gauge barrels).

Might be some better ideas out there...

Best, Tim