Kenny, are you sure the mags from the pawn shop are Security 9 magazines and not SR9 or SR9c mags, as those will not work in a Security 9. If it has a black magazine follower, it is most likely the SR9 magazine and won't work. I believe the Security 9 magazines have an orange magazine follower. They both look almost identical.

Kenny, sounds like you got a couple of SR9 17rd Magazines Sir. You will need toe Orange follower Security 9 17rd Magazines here : budsgunshop.com/product_info.php/products_id/119534/ruger+90691+security-9+value+pack+9mm+luger+17+detachable+2+pack --------- Cheers and stay safe!

Kenny, my best guess would be they may look similar but are likely for a different pistol. I'd try to take them back to the pawn shop and get your money back or to a gunshop. A gunshop might be able to help find out if it's for the correct pistol or not. If interested here's a link to spare 17 round magazines. Sorry but hope this helps, link here................ budsgunshop.com/product_info.php/products_id/119534/ruger+90691+security-9+value+pack+9mm+luger+17+detachable+2+pack