M249 build from disappointed to ecstatic

So I decided I needed something to rival my son’s ACR. The M249 V3 became that something. After buying one, getting it, fixing the gearbox that wouldn’t work (spring was jamming) and putting it straight on the chrono I was disappointed to say the least. The build of them is not that great despite what a lot of youtube vids may say and rate of fire was comparable to the glock 18!!
Enter the upgrades…so I went through our supplies and got to work this morning.
Gen 8 nylon gearbox, metal 18:1 gears, new plunger head, sleeve, 1.3 spring, o ring, custom length alloy barrel (from my ACR trials), I had to make a custom trigger and the gearbox shell was slightly different, XT 60 connectors, new wiring… we have 280 to 300 fps and around 20 rps. I have to get to the paint as yet and beef up some of the joints but it is a beast now and from my sons reaction might I have a hard time geting it from the lad!