We have tested and also agree these work great for the bottom of our Viptrays.
Gun Storage Solutions MULTI-MAG Gun Mounting Magnet (2-Pack)
Rubber coated magazine and gun mounting magnets
Quantity: 2 magnet strips; 4 individual magnets
Use one magnetic strip (2 magnets) for semi-automatic mounting (see pictures)
Use one magnet (cut strip in half) for magazine mounting (see pictures)
Made in USA