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You're welcome.
Combination guns are usally appreciated by classic-minded folks, who hunt in areas where both large & small game/birds are all "in season" at the same time, alowing the sportsman to take whatever game comes across his/her path.
I happen to like & use one occassionally - YMMV.
Your Drilling has chamberings that are less than modern & ammo is not commonly available everywhere (but can be ordered) - which usually puts their value somewhere near the $2K (+/-) mark, in the same condition as yours .
You would be best served, in regards to value, by surfing gun-only auction sites for "drillings", then locate another drilling (any unknown maker) that's much like yours in chambering, decoration & condition, to find out how much that gun recently sold for. (guns are really woth only what someone will actually pay for one - not what somebody "thinks", or "once paid xxx", whenever.
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