Originally Posted by L473ncy
I would say aim for between 370-380 (others will have different preferred FPS'es, some even opting to run 330-350 and .28's which makes the BB even slower). I really like that range of speed for outdoor play. No real need to go to 400 FPS, however that said I have my rifle shooting a consistent 395 FPS but before that I was shooting pretty consistently at 355-360 the only reason I upgraded the spring was because I was in the gearbox doing maintenance anyways and thought I might do the spring as well.
As for the spring, I'd say go for an M110. M100 IIRC should do between 330-350 (depending on the consistency of your seal and air compression). M110 will do ~350-380. At the end of the day you're not putting significant strain pulling an M110 so it's probably good enough.
As far as battery goes, 7.4V is what I'd recommend for most people unless they want the best trigger response and a higher ROF. As far as battery care goes, get a good balance charger. I highly recommend the Imax B6 charger and the highest Mah battery you can comfortably fit. Also don't overdischarge your lipo or you may damage it or set it on fire (I'm serious), when you hear the ROF starting to slow down then disconnect your battery and switch to a fresh one (also you can get a lipo alarm that attaches to the JST-XH connector and will beep when voltage is starting to get too low).
Voltage = electric potential difference (how hard current is pushed through the wires)
Capacity/Amperes = amount of potential work available to do, aka "juice". Generally it's 1-1.3 BB's per mah on most airsoft guns so for a 1000 mah battery should last around 1000-1300 BB's/gearbox cycles.
Okay, so you're saying a spring upgrade to an M100 or even an M110 will not require any further upgrades to the gear box or other parts? That seems contradictory to what I hear from most, although I have also heard in a few places that the stock internals of a Tokyo Marui can usually handle most spring upgrades without the need for more changes.
Also, for the battery, I'm still really only wondering if there is any particular brand and model of battery/charger I should get. Give me some specific ones to choose from, because I want something good (but not overly expensive, if possible) for both the battery and charger, but have no idea where to begin. So if anyone can link me to some specific choices that will fit this gun, or even at least just tell me what to google or something, I would appreciate that a lot. Same with the springs, though those sound like they would be easy enough to find. And lastly, for the spring once again, I'd like to know for sure if I really can upgrade it just a little without risking damage to the gear box or anything. I'm hearing conflicting opinions on this, so I'm still not sure. From what I can tell, the TM sigs can handle a heavier spring without other upgrades, but I don't know if that is a fact.