Have you purchased a .999 Fine Silver ( Pure Silver ) AA Coin and noticed it seems smaller? There is a good reason for that and here is the back story. You can find AA .999 Silver Medallions here which come directly from the manufacturer Wendells Inc.
A "normal" bronze AA coin is a Wendells Inc medallion produced with the same die and size blank as what you are used to seeing which is 1 5/16" or 34x2mm these existed until March 2020 in bronze (brass) and aluminum and gold and silver plated and lastly the .5 oz .999
Their manufacturer of silver blanks stopped producing .999 blanks in 1 5/16" and they could not find a new source. To keep the .999 line alive they had to make all new dies and buy the commonly produced 30mm .999 silver blanks. Those are .6oz so you get a smaller diameter but slightly heavier piece of silver.
As a result the .999 AA Medallions are back on the market but are a smaller diameter but thicker coin than what people would call a "standard" or "traditional" size AA medallion.