As far as optics go, never waste your time with repro optics. Get a holosun or vortex optic. Once you do it you'll wonder why you didn't do it sooner, especially when you're talking about low power variables...
The vortex strike eagle is excellent for the money and has a lifetime warranty. It's about €300 or so.
I haven't timed it personally, depends on ambient temperature but 15-20 sec on a stock mag and 25-30 sec on a modified mag to account for the extra volume inside the mag.
The problem is most people don't understand how to correctly fill TM mags. They expel air as you fill with propane to get rid of any air pockets. People think there's an issue with the fill valve and don't keep filling until liquid propane spits out of the filler. People not getting through 30 rounds simply haven't filled the mag enough. The green gas mod is optional and yields higher gas capacity in turn also increasing magazine pressure which will bump up the fps a little as well. There's no need to do the green gas mod, however there's really no reason NOT to do it too. It only gives you better performance over all.
Some guys here have fabrication skills, or 3d printers. We really need an adaptor for the Odin loader to load our mags similar to the GBLS DAS adaptor. Have a look.
https://www.gblsusa.com/products/odin-innovations-m12-sidewinder-speed-loader-gbls-das-gdr-15-m4a1-magazine-airsoft-gun
The only one you need is the airsoft innovation propane adaptor. Don't use the ones made of metal as they wreck fill valves. The plastic on the AI one is sturdy and I've been using it for 2+ years no-issue.
This is not true. The stock is milspec. I installed a Magpul MOE adjustable stock and has zero wobble or need to shim. Upgraded the buffer tube to the angry gun milspec sized one also and stock has same fitment.
Increased power and more gas capacity? Sounds like a win win to me. Just don't cut the tube TOO short, you'll get a lot of liquid coming out of the nozzle.
Leave the outer tube about 5-6mm above the actual fill tube on the valve.
Yeah there's actually probably the most kits available out of any platform. The kits cost more than twice the amount of the base gun with no internals at all. So yeah a kidney is required.