fa-mas spring
 

i was just wondering if anybody knows what the highest spring i can put in my famas sv1 without risking breaking anything and what kind of fps improvement it would make over a 1 joule systema spring.

the box itself is near indistructable, its the gears and piston you have to worry about. general rule of thumb is a stock piston can handle a pdi 140-150 equivilent for a seaon. stock gears can handle a pdi 170 or equivilent. although those are just generalizations, it matters on the use and abuse you put the gun through.
youd be safe to get the spring but i would reccomend a upgraded piston and silent piston head to go with it. your gears should be fine with that setup.

a systema 1 joule spring is what i have in it right now im actualy wondering what would be a good upgrade from that.

according to the spring commparisson chart this is one of the lowest springs u can get, it has this becuase the previous owner needed to limit his fps to under 250 i think.

and the gun is Janus DP's old famas and i think he upgraded the piston head, bushings, and gears.

That's like a System M90 (1 Joule), which is pretty much a stock spring, power-wise. Even the Systema M100 is considered a pretty "light" power upgrade.

I've run a PDI140% in mine for a while, doesn't hurt the ROF much ('down' to between 1000-1100 RPM) with a stock battery (8.4v 1700mAh), I'm pretty confident it won't hurt the mechbox, and it delivers a noticeable power increase. I've used a System polycarb (v2/v3) piston, alum piston head, and metal bushings. Kept the stock gears, they aren't showing any abnormal wear.

back in the day the pdi 140% i bought for my mas upgrade managed to snap the bevel gear in fucking 2
wish i had a digital camera back then
easy replacement with a v2 gear and went down to a guarder 120 spring