Gearbox for SR-16
 

Is this set ok:

http://www.wgcshop.com/pcart/shopper...ts%20for%20AEG

http://www.wgcshop.com/pcart/shopper...8_cat_Gearboxs

http://www.wgcshop.com/pcart/shopper...tema%20Springs

The spring will be m120 because the Guarder spring will do about 430fps.
Especially I want to know if the gears are good.

up

Just installed one about a month ago into my P90. So far no issues except the screw holding the piston head onto the piston came off some how. Just make sure that you have a strong enough battery to push that spring, 9.6 or higher.
When I brought it into Canada they border officers studied it fairly hard to determine what velocity it would put out, it doesn't give an actual FPS reading on the package so ask whoever your buying it from, to makesure the invoice clearly states its true velocity.
The FTK should run fine in your stock shell, but if you'd have a greater piece of mind with a reinforced shell, then go for it.

There are reports of Systema springs snapping. Might want to go with a Guarder SP110 instead, a Modify S110 or a Prometheus MS110.

Customs has no business stopping springs.

Velocity doesn't matter, and it's not a restricted item.

Internals are not restricted as it does not affect the appearance of the gun. However, if the internals will push the velocity over the 500 mark, it is restricted.