Not ejecting properly

[LR1955]

So what is the ideal buffer and recoil spring? I'm using a Magpul UBR stock and unknown spring and buffer. I have used this lower on other uppers and it functioned perfectly so it never occurred that this could be the issue...............Roger

Roger:

And it probably isn't the issue. That's why I listed it last in terms of potential problems. The question is if you have done the other checks first.

The ideal buffer and spring combination is the one that works. If you are using a carbine length stock, use a carbine buffer and spring. A standard rifle stock -- use a standard rifle buffer and spring. Very few times will this not work. And in those times, most likely the problem is the gas system and not the buffer or spring.

LR1955