I can't go with stock guns anymore. I have to always tune everything to my liking,especially shimming. Most stock shimjobs I see are pretty bad,no OEM seems to shim bevel-pinion(I know why,it's a very trial and error process so I can sort of excuse that)
On most stock guns. I find most parts to be pretty decent quality. Only thing I can name that I don't like are VFC pistons and hop up units,Marui sector gears(The rest of the gearset is surprisingly pretty decent,mesh well with most brands I've found) and ACM air seal parts and hop up units. Love me some ACM motors however,especially the stupid 22+ TPA neo torque monsters some are starting to come with,which is a mixed bag because fuck consistency amirite
I,however being the broke teenage git I am,always try to DIY something. Hop up unit cast using molds made out of dogshit? 1 euro 50 worth of brass shim stock,sorted hey. I finally have access to a milling machine at school so my hop unit shims I make don't look like they are cut by micheal J fox while wanking.
You gotta love the chinese guns though,pretty good at churning out mahoosive amounts of guns as cheaply as possible.. They make up for piss poor hop up units with high FPS,they make up for bad air seals with Massive spring powers,they make up for an overly stressed build with really strong gears and pistons,they make for the loss of money on better materials by casting them roughly,they make up for heavy loads with massive torque motors.
Now if only they hired QC departments and stop casting their pot metal parts using molds made out of chicken skin,they'd be well grand.