S&T Upgrade Spring for M40A3 Series Airsoft Sniper Rifles - 500 FPS

"Installed this and a tight barrel, gun shoots so much harder. Haven't had a chance to Chrono yet.

For anyone wondering, yes this does fit the Matrix/Double Eagle M40A3. Very easy modification.

"Works great! Just installed it in my M40a3 sportline, and the install only took about 5 minutes. Was shooting around 510 with .20 bbs, but might drop a little bit as the spring settles with time. Also, I recommend a minimum of .32 gram bbs. If you can hop heavier, then the better.

"This spring is longer than the stock spring, but it works all the same. I put this in my ASG M40A3 Sportline.

"Little longer than the stock spring, but went from barely getting .4g out to 240ft to launching .46g bbs out to the same distance without much trouble. Haven't had a chance to chrono yet, but seems like it will be around the 500fps range.