Depends on your threshold of unusual.
Hardware stores, general stores, country stores, quasi-convience stores having a gun counter not unusual. Not as much any more, but dept stores used to frequently have a gun or gun/ hunting/ fishing dept.
Yes, one of semi local establishments used to be ( owner's first name)'s Coins & Guns .
A different catagory is where the owner of an established unrelated business uses the pre existing properly zoned and licsensed premesis for an FFL , but doesn't have a Publically visable gun counter, nor advertise it to his usual customer base. I've seen this at a liquor store and an industrial chemical supply house.
But I guess the most unusual was a store that was half C&R type firearms, half adult sophisticate literature ( aka porn).