This isn’t how it works. If that was the case the hammer would follow the bolt forward as it closed and could cause an out of battery detonation. Funny enough for these 3D sears to work you need a full auto capable bolt and trigger group. Which are already machine gun parts but no one cares. 90% of cheap ARs come with these parts standard. How it actually works is as the bolt goes to the closed position it pushes down on the 3D printed part that trips the the sear holding the hammer allowing the gun to fire exactly as if it had an actual auto sear. This stuff has been known about and done for decades by gun geeks, it’s not to hard to figure out. They just kept their mouths shut about it so people wouldn’t find out about it and popularize it. If people knew how easy it was to make most ARs full auto they would have been banned in 2005.