A few weeks ago I went through Manchester as a passenger. I had a plastic splint on my arm. I offloaded everything, shoes and belt included, and still the arch 'pinged' me. Very polite security staff, very effecient, went over me with hands and wand. I volunteered to take the splint off, no problems, all very quick. The only metal on me was press studs on the trouser pockets - not even a metal zip.
coming back, a week later, went through security at my departure airport, no 'pings', no problems. only when airside realized that I had a huge handful of change I had forgotten about still in my pocket.
Point is, given the planning that the baddies seem willing to put into their efforts, it would be very simple to test the screening at different airports and choose the one that lets you get stuff through.