I'm using this one with a 50mm obj. scope, so yes it will work http://www.americandefensemanufacturing.com/view/product/298/ it may be a little higher then needed for the 42mm you're looking at but if you ever go to 50mm you will not need to buy a taller mount.
Look here> https://www.primaryarms.com/American-Defense-ADRECON-30MM-p/ad-recon-30.htm