The prone accessing inventory animation does not stop playing until the player moves or uses some sort of other bind (switch weapons, vault, etc). Firing the primary weapon does not stop this animation, nor does aiming down sights, meaning that all shots fly off to the top left of the screen.
Here's a video to demonstrate: http://www.youtube.com/watch?v=oIrNuZyJYXc
This does NOT affect side arms (pistols). Firing after accessing the inventory in prone brings the pistol back down to the firing position.
It's also one of the coolest looking glitches.
Sorry if it was already posted! Couldn't find it.
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