It's really not all that big of a deal. Gear on one side drives a rod that connects to a gear on the other side.
It's not like it's a v7 box or anything!
The VAT registration threshold for EU business is £85,000. Below that and they don't have to register, once they do though, they'll have to do accounts for HMRC (as well as their own government) along with all the additional cost that entails. For someone like TG I can't see that the volume of sales is worth it. Gunfire will still ship to the UK because they know there's customers there but still insist on a minimum order of £135 because that's where the responsibility shifts from them to the customer. TG stopped shipping over to the UK because of UPS and the hassle that their utter clusterfuck of a service has caused them. GF just started using a different courier instead (GLS).
Gotcha.
To be honest, it's only the Aster or Titan that do that to the best of my knowledge (I'm sure someone with better knowledge of Perun kit will be able to clear that up).
If you're not looking for something that fits inside the gearbox then literally anything that wires to the trigger contacts. The only thing I know of that counts the BBs as part of a Mosfet is the new Gate thing that mounts on the side of the rifle and connects to a Titan via bluetooth (so that's out).
Not sure on the Ham licences but the business ones only licence you up to 5W. Plus, I'm not sure where you go mountain biking but unless your mates are in another country I can't see you needing 8W!
You can definitely get Kydex ones made https://www.kydexcustomsuk.com/extras/custom-smg-holster
and there is a fabric one made by Leapers/UTG but I think it may have been discontinued. As mentioned above one of the universal adjustable ones may be your only bet, alternatively you could sling it and use a weapon clip to stow it on your belt.
TL:DR
Out of:
Longbow, Valken, ASG Open Blaster, Nuprol RZR, ARES, Geoff's, Psionic Upgrades, 6mm Ammo the best groupings at 20m were Ares and 6mm Ammo but they were all much of a muchness apart from the Valkens which seem to be a bit worse.
Horses for courses - part of the purpose of proper tactical lights is to dazzle your target hence they go into the 1000's of lumens. Navigation lighting is usually more subtle so you can see where you're going without (completely) giving away your position.
So if you want to see where you're going but not crisp up vegetation or strip paint at 100m then get something in the 200-600 range. If you want to be "that guy" then go big or go home. Preferably with a strobe.
Sure, mine's a MK12 built with an E&C M4 receiver but the stock was second hand. There is a Cyma one that has the adjustable stock plate that is a bit more SR25 accurate though.
This one comes with all the parts you'd need: https://www.davescustomairsoft.co.uk/external-parts/stocks-and-stock-related/cyma-m4-m16-aeg-full-stock-with-adjustable-butt-pad.html
OK, you'll need 1) your chosen stock, 2) a long ass stock screw (might not come with the stock), 3) a suitable sling plate (something like this one is good https://www.fire-support.co.uk/product/kingarms-metal-rear-sling-adapter-m16-solid-stock)
The reason for the sling plate is that the M16 style stock has a step in the front end:
You'll need that plate in there to keep the stock solid when you screw it on.
Then it's just a case of pulling your wiring through (you may need to extend it or get an adaptor) and screw the stock on with that long ass screw!
Also - I have a handguard for sale if you want to make it more "SR-25ey"
Might be worth remembering that TWG may have had a delivery notification from UPS in which case they may say that they want payment or the goods returned.