I heard something loose in the AR15 and when I disassembled it the Buffer stop spring and pin was floating around in the lower. I reinstalled the spring and pin but after assembly again and cycling the bole a few times the spring and pin were again loose in the lower again. What holds the pin in place so it will not come out? How far should the pin be sticking out to stop the Buffer Piston? Thanks

The receiver extension captures the buffer retainer and spring. Your receiver extension is not correctly installed. This is what it should look like:



Click the photo to enlarge.

Install the buffer in the action spring and just push it in. Cocking your hammer may make it easier.

That is a great detailed picture from Weaponrevolution.com and I presumed there were a series of pictures of the entire AR15. I went to the site and could not find them. Could you please give me a hint to where I could access the images?
Thanks––-Bill

Best I remember , the buffer has 3 flats cut in its rim . These make it easier . Then rotate the buffer so that a round ( un cut ) segment lines up with the pin .

To get the spring past the pin , I just " screw " the spring in .

God bless
Wyr