In this paper, indirect microwave holographic imaging of concealed ordnance is demonstrated. The proposed imaging technique differs from conventional microwave imaging methods in that it does not require the direct measurement of the complex field scattered from the imaged object but mathematically recovers it from intensity-only scalar microwave measurements. This brings the advantages of simplifying the hardware implementation and significantly reducing the cost of the imaging system. In order to demonstrate the ability of the proposed technique to reconstruct good quality images of concealed ordnance, indirect microwave holographic imaging of a metallic gun concealed in a pouch is carried out for airport security imaging applications. It is demonstrated that good resolution amplitude and phase images of concealed objects can be recovered when back-propagation is applied.