Dude, that is awesome!! Most if not all of what I needed to know! I'm not beyond putting a longer barrel in with a silencer to protect it! But that deffo gives me a starting point!
If you put in a much longer barrel & silencer/suppressor then you ruin the look & concept of the FireHawk....
About a 140mm of some mp5k's "should" be do able as is
But people have taken a FireHawk put a longer barrel on and it just looks wrong....
Raider Short is about 233 already known common as muck CM receiver but well proven no mosfet of course
FFR A2 is about 260mm - this was one I had my eye on @ £155 but was out of stock on black friday 15% discount
(same size barrel as SR-L but £30 cheaper - maybe outer barrel is polymer vs metal on SR range)
SR-S is about 205mm
300BOT is 205mm but just basic mosfet CM receiver
CM18 is 275mm no mosfet CM receiver but sexy black/tan or tan/black
Going too nutz and spending money on exterior could be spent on hop/bucking which is where you get the range/accuracy from.
Try not to reinvent the wheel, consider all options and get the correct base gun for your requirements.
What with G&G doing an extensive range it can be a bit tough choosing just one though but inside they are nigh all the same just different cosmetic externals
my pick would be the FFR A2 ATU 3rnd burst mosfet atm as value for money - 260mm barrel without vivid CM receiver
but as said I haven't got one - but wish I had got one for about £135 with discount on BF
LWA might have some in stock but I'm trying to ease up buying more stuff I never get round to using