A couple of decades ago the word was a 2 shot burst would replace the 3 shot burst with an A4 rifle. It never came about, getting it to work right just didn't happen. And now it did. One working version is called the Echo Trigger from Fostech. It is pricey, but far less than a class 3 transferable. And it increases your firepower. If you pony up the 500, mag dumps are not what you should do with it. Make it ready for the end.
[video=youtube;eol8fvMfENc]https://www.youtube.com/watch?v=eol8fvMfENc[/video]
[video=youtube;eol8fvMfENc]https://www.youtube.com/watch?v=eol8fvMfENc[/video]