1. Don't pack BBs in your cabin (carry-on) baggage.
I had a bag of BBs seized at the security check at DUB on Friday. They wouldn't allow them in the cabin, even after I explained that they were harmless and so on. Wouldn't budge at all. They did offer to let me return to the checkin desk to have the bag put in the hold, but since that would have cost more than buying a bag of BBs at the destination I surrendered them and they were binned. The screeners were quite nice about it, but would not be persuaded. The picture of a gun on the label only strengthened their resolve.
2. EI have a clause, buried deep within their baggage regulations, that you can only have one gun per case.
"** Sport guns and ammunition cartridges will only be carried subject to the following:
Guns are to be dismantled.
They will only be carried in the baggage hold of the aircraft.
They must be packed separately from other baggage.
They must be packed one gun per case.
They must be available for inspection by security.
Ammunition/cartridges must also be loaded in the baggage hold and must be available for inspection.
They will be subject to a max baggage allowance of 30k including arms and ammunition.
All government and legal regulations must be complied with.
All documentation and licenses are the passengers responsibility.
Subject to an extra charge for the carriage of sports guns and ammunition."
They didn't apply the one-per-case limit on my flights, but it does exist if they wish to. BTW, the checkin staff were brilliant. I had to do a bit of explaining as they'd never heard of airsoft or replicas, but apart from the extra few minutes to wrestle with the computer they were fantastic.
3. Outbound procedure at LHR.
When you declare a firearm at checkin, the bag will be tagged as a normal bag. You will be brought over to the ticketing desk, where they will take note of the tag number. You can then take a seat and wait for a nice man from Group4 Securicor to arrive. You then fill in and sign a declaration form (describing the item(s) as a "Realistic Imitation Firearm"). The G4 person will ask you to describe what is in the case, what it looks like, and whether there's anything else in the case. Then he takes it away, and the next time you see it is when you land. Mine did not arrive with a firearm tag on it, and it just came out on the carousel with all the other bags.
Personal opinion: Due to the hassle involved with packing – this can't go in the cabin, that can't go in the hold, etc – and the cost of bringing 3 bags, I would probably not choose to fly to an airsoft event in England again. It was far worse than the bureaucracy of declaring imitation firearms (that bit actually went fine, both ways). They didn't bat an eyelid in Heathrow.
BTW, SO19 are now using EOTech 552s on their MP5s.
Anyone posting that these regulations are silly deserves an infraction for wasting everyone's time and bandwidth. Please spare us. I'm pointing these things out to smooth your journey at the aiport.