I put this spring in my CA M15A4 as an upgrade, yet stay under the field limit of 400 FPS. I also learned that a number of reviews show that Guarder springs tend to be stiffer than most. I added this with a MadBull 6.03mm TBB and a JBU M120 Full Tune Up kit. The Full Tune Up kit came with:
JBU Aluminum Air Nozzle
JBU Aluminum Piston
JBU Aluminum Piston Head with Ball Bearings
JBU Chrome Cylinder
JBU Aluminum Cylinder Head
JBU Aluminum Spring Guide with Ball Bearings
All of these made for great compression over stock on my M15A4. Also the ball bearing piston head and ball bearing spring guide add a little preload on the spring. In the end with this SP100 spring, the gun was acheiving between 365 and 400 FPS on 0.20g BBs.
Very nice spring with the non-linear segments where the coils are denser.
Actually more like an M110 power-wise, but I have other upgrades to get the most from this spring.
2008-02-02 12:04:52 D. DAY
For: Guarder SP100 spring
Well, I got this spring for my Jing Gong G36c (along with metal bushings, metal spring guide, and polycarb piston). Before my rifle shot 370, way too hot for CQB. But this spring is giving me a constant 340 w/.2's and the ROF has increased a little bit because of the lighter spring. I definitly reccomend this product, I'm getting an sp110 for my JG M16A4 so I'll do a review on the fps that spring gives me also.
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