I'd suggest moving section 1.3 before section 1.1 - might be a bit tricky to explain guns to buy etc. without having explained AEG, GBB etc.
Personally, I think it's essential to give a lot of internal info. At the bare minimum an explanation of all the various parts inside an airsoft gun, but also (possibly to be added at another date), detailed, weapon specific maintenance, disassembly, upgrading etc. But it could probably be done as an add on, once the core is already up and running.