Have been to Kittery Trading Post many times. They have most everything you would ever need. I have never bought anything on line from them but I wouldn`t hesitate if I was looking for that item. They are located on Route 1 in Kittery Maine about 2 miles from New Hampshire.
I've visited there many times and have used them for a FFL purchase. The retail store is several hundred thousand square feet of most everything you could image for outdoor pursuits, hunting, fishing, camping, hiking...etc. A large portion of the second floor is devoted to guns and accessories with racks and racks of used guns. My latest visit was at the end of August, 2020. At that time, they were wiped out of almost all reloading components and powders. The used gun racks were mostly barren, but that was the norm most places after the "mostly peaceful" demonstrations in large cities around the country.