You are correct, it is in fact "A and A" but the American convention has been "A-Y-A" for so long I think people might wonder who you were talking about if you commented on an "A and A."

No matter...still beautiful guns.

Ps. Just as common a mistake, I see, is when people confuse one man's initials vs the last initial of two proprietors.

W.H. Baker was one man.
W & C Scott references two men in partnership.

Nudge