Great feature on AR9 Pistol build
I was fascinated with the engineering on this product and wanted something to shrink the overall length of an AR9 pistol build while still allowing for it to remain functional in the folded state. Completed the build and was able to push about 200 rounds down range the same week. Everything worked great. I ended up using the "medium" weight BLUE spring on the blow back system. No feed issues, recoil was like...well, a 9mm pistol recoil. With the tailhook brace added on, this was very stable in the deployed position. In the folded position, it fits easily in a 3-day ruck style backpack. Frankly, this whole project was just plain FUN!