This will soon be available at Echigoya for those who want a stronger recoil effect on their Tokyo Marui New Gen M4 SOPMOD... "Today a prototype of 401 grams Heavy Weight recoil unit made of solid brass (machined by Tirador of ARS) for Tokyo Marui m4A1 sopmod was just tested in the fully upgraded Tokyo Marui NexGen M4A1 and the recoil and kick was so hard and crisp.

The weight of this is 401 grams while the original is 282 grams, this is a 119 grams difference.

This recoil unit will only fit to ARS buffer tube. It won't fit stock tokyo marui buffer tube and others. Here is the video: the recoil and kick is so hard. Awesome!"