Started a new build this evening. When I got to the pivot pin install, the build came to a quick halt. After installing the pivot pin, I found that the pin would NOT move by thumb pressure either way. I was stumped. Uninstalling wasn't too difficult with the hole through the pivot pin. No big deal there. I double checked the spring I used - correct. The detent was also correct. I had also used the correct pin. Couldn't figure it out. Then, I had an idea. I did a web search for the correct depth of the recess for the spring and detent. On a site I found that the "correct" depth of the recess was 1.125". I measured the recess on my Aero lower and found that it was 1". Aha! Too much spring tension due to a too short recess. My first move was to find my cordless drill. I planned to drill another 0.125" to achieve the "correct" depth. Thank goodness the batteries were dead. While I was waiting and mildly fuming, common sense smacked me in the head. I decided to snip 1/8" from the pivot pin spring. I did and the pivot pin installed with no problems. What felt like the correct thumb pressure to move the pivot pin in and out was achieved.

My question is this: Is the 1.125" depth correct?/Is my Aero lower out of spec?