Hi-speed ("slow motion") videos from Tripp Research.
From Scott F.:
You can see the bolt bounce when the AR15 bolt cycles. This is why one needs a H1, H2, or H3 buffer in full auto fire in a M4.
In the last vid of the 1911 (closeup of the muzzle from the right side), you can see how much time there is from the when recoil starts until the bullet leaves the barrel, hence the need for follow through on the trigger and sights.
Pretty kewl stuff here, you may want to bookmark the page.