Prometheus Non-Linear Irregular Pitch Airsoft AEG Upgrade Spring (Power: MS90)

"Bought the MS 70-85 for a CYMA AK-47 60th anniversary edition rifle. We play mostly CQB got the gun from a mystery box where excited to use it. But our field is limited to 350fps. We bought a M-85 hoping to take it down below 350fps. This kept the gun shooting about 370fps+. So we bought this hoping to get it below 350 without modifying anything inside the gear box besides the spring. This indeed did take us all the way down to 320 FPS. If you are looking for a spring to decrease your FPS below 350 and are using a longer gun try using this spring.

"A lot of people say a spring is a spring but when it comes to this one. The Prometheus spring has been the most reliable spring that I have ever used. I used it in all my airsoft guns. I highly recommend getting this you won’t be disappointed

"Could I put this in my Matrix M4?

"Threw it in my KWA RM4a1 and it upped the fps from 380 to 425 with .20's and 332 fps with .32's right around 1.52/55 jouls. My gun is compressionly sound so yeah I recommend it it works great.

"Great spring, works great in my Echo 1 Rec7.

"I love this spring!!! i'm shooting 509 FPS in my M4 and i'm sure that i don't have the best air seal , i still have some fine tuning to do but i am very happy with this spring!

"very good spring! with a JG blue motor and a hefty 9.6 you can run it fine. (with a sorbo and upgraded gears. im running SHS) if you want a higher FPS this is the spring!!!!!!!!!!!!!!!!!

"Good spring! I installed this in my DMR Barrett and it is getting 480fps +or- 3 FPS W/.2g bbs. Overall very impressed, but it is a pain to install.

"AMAZING SPRING!!!!!!!!!

Works AMAZING in my SVD!

great buy!!!!

If you need a good spring for a high powered sniper.... GO FOR IT!

"Great spring for 15$. HOWEVER. This spring gives you an average output of about 673 fps. Which is a huge safety issue. Playing with this is really for experienced players only. I'm not kidding here. I play with a minimum 100 feet engagement rule. Within 100 feet it really could do some damage. But with the correct clothing (i.e. vest, bdus, facemask, etc.) It's not too bad. IT WILL MAKE 'EM CALL THEIR HITS!!
Btw to have this spring in your gearbox, you need to make it ready to pull it...

I've got a Prometheus High torque steel gear set, 6.03 590mm Prometheus tightbore, a G&P hard piston, angel custom hard 70 bucking with a polarstar spacer, and a G&P m180 satan motor. Everything else was left stock (Had a g&p 8mm gearbox wired to deans. Shimmed and tuned well).

Overall a great spring... just make sure you know how to use it... and safely use it!

"When they say it, they mean it. This is for experienced players ONLY. If you are new to Airsoft, do not buy this spring. Go with the 550-600 or the 400-550 for 10.00$. This is intended for very serious hardcore veteran players. I used this on my G&G Limited Edition Blowback Machine Carbine (Tan) and my friends hate to face me. Again, this is for experienced players only. Thanks for reading.

"Good spring, identical to the systema. May want to save a few bucks and go with the systema instead. Also the paint tends to flake off after awhile.

"Spring is black not purple or red for the m170

"This is not a good spring for a DSG. The progressive sections are far too soft.

"replaced my stock m120 which was shooting at about 360-370fps with the prometheus m135 and saw no increase in fps. If anything I lost some fps(it was shooting ~340-355). This was after putting several hundred bb's through it to potentially loosen it up.