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.
A few things to consider: compressed air at that pressure is dangerous, there's no getting around that so a good quality unit is essential. A good quality compressor is expensive, this isn't which rings alarm bells for me (trust me, it really isn't expensive - my airbrush compressor only went to the hundreds of PSI and it cost three times as much as that). Needing to change cooling water every 30 minutes would be an issue for me, lack of any moisture trap concerns me too.
I'd go with something more like this: https://www.uttings.co.uk/p130854-air-venturi-nomad-ii-4500-psi-portable-pcp-compressor-av-mcomp4500-2/#.YTHnp45KiHs
AT LAST! Someone else that shares my view of Gervais.
I was working up in York, years ago, one of the guys I was working with said "I like that Ricky Gervais, the more I learn about Reading, the funnier he is". Pretty much sums him up really (for the uninitiated, Reading is a shit hole, Gervais comes from Whitley which is the shittiest part of said hole).
Turnigy S60 https://hobbyking.com/en_us/accuell-s60-ac-charger-uk-plug.html?wrh_pdp=1&utm_source=google&utm_medium=cpc&utm_campaign=google_gb_shopping&countrycode=GB&gclid=CjwKCAjwj8eJBhA5EiwAg3z0m8dxhcJW3kfWGwHSe3aQ4RZ2DHGLkr3Ca2v_G1ErceiahHhtZtmWkRoC5DMQAvD_BwE&___store=en_us or SkyRC S65 https://www.hobbyrc.co.uk/skyrc-s65-65w-6a-ac-balance-charger?gclid=CjwKCAjwj8eJBhA5EiwAg3z0m50ROGc3I6EQrpyXmamlISS4cLkI8u8he-BpAzP8VhXpKE8h7nMevhoCaSkQAvD_BwE
Batteries 7.4v 2S or 11.1v 3S - Turnigy NanoTech, Vapex, Giant Power or if you're feeling flash, Titan Power LiIon https://www.airsoftanonymous.co.uk/pages/titan-power-collection-page
I have a NBB Desert Eagle from way back when the gas went in the gun and the mag looked like a pez dispenser. Now THAT'S sad when you pull the trigger!
That's what I use for the piston slides. I use their LT2 grease for the actual gears https://www.amazon.co.uk/Abbey-Shotgun-Airsoft-Spring-Molybdenum/dp/B071FYQGLJ/ref=pd_bxgy_img_1/257-2017919-9316805?pd_rd_w=80UpA&pf_rd_p=c7ea61ca-7168-47e3-9c8b-d84748f5b23c&pf_rd_r=MPA4EXXRH2YD7V30JMT4&pd_rd_r=bcd4b62f-49cd-47e0-855a-fc297ef2a669&pd_rd_wg=4VEtA&pd_rd_i=B071FYQGLJ&psc=1