Systema M100 Irregular-Pitch Airsoft AEG Power-Up Spring (340~380 FPS)

"Great spring if you want to downgrade for an Indoor CQB setup or if you are converting to a high speed setup.

I've got this in my MP5 (with too many mods to list) and it chrono'd at 330 fps. If you combine this spring with a high speed motor (I've got the G&P M120 HS motor) you can expect a ROF from 20 to 50 bbs/sec depending upon your gearset and other internal components.

Great value upgrade!

"With this spring, a Tight bore barrel and the gasket mod I have seen this spring shooting 380 with .20's in my M16. Before these mods it was only putting out 315, couple that with a 9.6v battery and a high speed motor and you can expect 22 rounds a second