no it will not it is to short for the full size gripand only fits the compact model here is the correct 10 round mag for the full size budsgunshop.com/catalog/product_info.php/products_id/712013067/ruger+american+pistol+9mm+10rd

Kenny, no, it will be too short as it is a compact magazine. You will need the full size 10rd magazine here Sir : budsgunshop.com/catalog/product_info.php/products_id/712013067/ruger+american+pistol+9mm+10rd

No, that magazine is short to fit the compact version of the gun while model 8661 is a full "duty" size frame. The full size limited capacity 10-round magazine is #0514 here: budsgunshop.com/catalog/product_info.php/products_id/712013067/ruger+american+pistol+9mm+10rd and the full 17-round capacity version of it (if it's legal in your state) is #0510 here: budsgunshop.com/catalog/product_info.php/products_id/5756/ruger+mag+amer+pstl+9mm+17rd

Kenny, Yes, this is the magazine that model 8661 comes with.