4M lengths of stainless steel wire with loops in each end, attach one end to the weapon by threading the other end through the eye and then either thread a heavy chain through the eyes at the other end or padlock them on.
Might be an idea to then secure chain to a vehicle.
If you speak to the RRT or Recruiting Group they will give the low down of Risk assessments and paperwork you need. A lot of the teams that came up to my area brought show weapons, others couldnt get permission by their units. It would depend on security issues and on the paperwork request to the local police that you have to submit in advance, but the local AFCO/ACIO would be able to tell you more. Sorry you probably realised this already.
It can be done, as mentioned by GoodIdeaAtTheTime...
However, you leave yourself open to every chav with 50 miles descending on you, having mobile phone pics taken pointing weapons at each other and asking stupid questions like 'have you killed someone....' or telling you how hard they are...More grief than its worth, I suspect....
Even with the measures outlined, I'd be very twitchy about having weapons round without an eagle eyed watch on them...How easy would it be for example, for someone to remove the gas cylinder and rod even with no prior experience of the weapon?
Unless of course, you're going to a 'closed' recruiting event, such as a school careers night, in which case the security of the location, and possible benefits could be weighed against the above.....
i've just done a funday at a local football club, we took a rifle, a lsw With cws, and gpmg in sf role, the conditions attathed to us being allowed to take them out were, that they had to be chained to the rovers (for security), and no-one was allowed to handle or touch for h&s reasons
I have to agree with you on the weapons display. We have also used rappeling and fast rope demos. In some large gatherings, where we had a booth set-up, like at local airshows, Armed Forces Day, etc. we even used a small unit parachute operation. Amoured vehicles are always a crowd gather as well.
(I can remember a few of these, as we always seemed to land on the runway! Ouch!)
G20 - The use of weapon displays etc is covered under RG Outreach Instructions, you should have a copy in your TAC if not get the PSAO to get in touch with the Brigade Recruiting Advisory Team (BRAT), I'm sure they will point you in the right direction. But the should be deactivated and chained to a secure point, speak to some of the Army Recruiting Teams they should have some. If in doubt PM me and I'll put you in touch.