Heckler & Koch’s Gray Room is a pretty special place for gun enthusiasts, housing the company’s collection of custom and prototype firearms. It is, therefore, pretty hard to have a good nose around.

Help is at hand, though, in the shape of a new iPad app from author Jim Phillips and photographer Eric Eggly, which features photos of the prestigious collection.

The H&K: The Gray Room eBook, which sells for €7.99, lovingly documents the entire collection making it, apparently, a resource that firearm enthusiasts and aficionados will come back to again and again.