I wonder what kind of trouble I'd be in?
I've posted photos of myself on Facebook holding actual, real weapons: AK-47, AR-15, Magnum 357, CZ-75, 12 Gauge Shotgun, Uzi and a TIGR Dragunov sniper rifle. I even had one of these photos as my profile picture for a good few months.
(I visited a shooting range in Prague while on holiday a few years ago. I also no longer live in the UK, so I'm not really concerned about sharing this information here)