I've got a question about an new to me, DPMS, 6.8mm model #M-150. I noticed that the FSB is canted a little to the left. I'm going to try and remedy the problem but have to wait until I can get a fixture with which to hold the receiver in a vise. Until then, I've got the upper and lower separated. I've noticed that when I raise and lower the forward end of the lower assembly, with the stock removed, I can hear and feel something sliding in the buffer tube. Is that a normal sound? I had originally thought that the rattling that I was hearing was coming from the stock only. There is spring tension when I push on the end of the buffer.
This is my first AR type rifle. Please excuse my ignorance of the subject. Tried a search but didn't really find the answer that I was looking for.
Thanks for any help, crispy