I have an src m4 plastic series (rear wired if it helps) and the two little loops that attach the upper reciever to the lower snapped off. As a result I need a new one. http://www.airsoftworld.net/src-nylon-fibre-m4-receiver.html. This is the reciever that I believe came stock with the gun. I was looking at this one http://www.ebairsoft.com/dboys-metal-body-marking-p-6844.html to replace the broken one and I wanted to check that it would be compatible. If not, could anybody recommend one that would for around £30. Thanks, GingerBreadMan