Hrm, I don't think any got started sucessfully in the UK. There was one guy who has been around here that claims to have armed warship;s in England, but I haven't seen pictoral evidence. I know AusBG runs exclusively big gun (and I think 1/4" only?) because of some legal fun they had to go through just to be able to play. As I said before though, I would get some local legal advice and/or check with the local law enforcement before committing to arming a ship. Though nothing to stop you from doing everything except arming it, you'd still have a fun warship to sail around.
Ausbg runs three calibres, 3/16, 7/32 and 1/4 We cant use the .177 bb as they are firearms ammo and as such strictly controlled. Weird how the law works isn't it?
Don't call them bb cannons. 4.5mm ball bearing propulsion device might work better. 4.5mm = .177" 500 Pcs 4 5mm G16 Hardened Carbon Steel Bearing Ball | eBay
Try stainless steel. Should be infinitely reusable! 2500 Pcs 4 5mm 0 1772" 316 Stainless Steel Bearing Balls Grade 100 G100 | eBay
