hitmanNo2

Well yes, so did I but there's this thing called the VCRA now...

VCRA

In subsection (7) “modern firearm” means any firearm other than one the appearance of which would tend to identify it as having a design and mechanism of a sort first dating from before the year 1870.

https://www.legislation.gov.uk/ukpga/2006/38/section/38

It's a rather peculiar date, and may actually be intended to cover cartridge revolvers - the Colt Single Action Army was developed around 1869 and trialled in 1872. So that cap gun might very well be a "modern firearm" by that definition.

The real answer is that they're "getting away with it" because nobody really cares.  We know that there are airsoft sellers flogging unambiguous RIFs without real defences, and what would the defence be for this paintball "marker"?

https://www.bzpaintball.co.uk/tippmann-stormer-elite

Or for that matter, this gel "blaster"?

https://gelweapons.co.uk/collections/slr-gel-blasters/products/slr-gel-blaster-brown?variant=47816758591823

You might argue that those aren't non-firearm airsoft RIFs, but instead some super-secret sub-category of airgun firearm that isn't really an airgun firearm, nor a RIF.  I've seen claims that paintballs guns aren't considered as airgun firearms because the ammunition is (or rather can be) frangible, but I can't recall being pointed at any specific legislation or case law.

It's all a bit silly really isn't it, is my main point I guess.  Newcomers to airsoft pissing about with two tones and then we get stuff like this.