GFC is GunFire Custom, meaning it's kjw in your case but they tinker with it. They relube, probably reshim AEG gearboxes, maybe change the spring and test it. I don't know what they do with gas guns, probably just relubing, testing.
I don't get it how it works. The nut seems to be glued in and the bottom part doesn't have a nut. So it seems somehow there is a threaded rod that can move up and down but can't turn.
Not worth £1. Useless as a sniper rifle out of the box, breaks quickly and there are no parts for it to upgrade or replace the broken ones. Not compatible with anything.
The position of the front sling mount is unique to this, if you see that, it's this model. It's an AGM originally.
Not to mention that you can get a brand new Bar-10 for that price and that's a great choice. When it is in stock in Poland that is.
The current JG versions have that vertical BB tube on the hopup itself. All the other versions have it on the magwell. If the magwell and the hopup has it, just cut it off from the magwell.
Make sure the G36 mag fits in the pouch you choose. A single G36 mag will fit a double M4 pouch if there is no separator in it. Also the g36 mags has those things that clip them together and they catch on anything horizontal in the pouch. Elastic pouches won't work either. You can get an M4 magwell for the g36 though, that solves this problem.
Excellent choices.
Get at 0.25 or heavier BBs. Don't go for the plate carrier, it's very cumbersome. Get a chestrig or a molle belt or both. Helmet should be the last on your shopping list.
Get good boots, with good socks and maybe a gel insole for it.
Edit: Proffrink ninja'd me.
1000 on auto is less wear.
When you pull the trigger the battery gives a higher current for a second (that's the second C rating on the lipo, but other types has this too).
As the trigger contacts move close to each other, there is a tiny spark just before they make contact. This burns through them in time.
Getting a mechanical system to move from a stop always require more force than keeping it in motion.
If the system is too fast and on auto the next cycle starts before the piston fully returns then it strips the piston or the gear so that would be more damaging. It's a similar effect as a bad AOE.