Originally Posted by Secondhand_Hero
i've heard they are less than comfortable and rather awkward.. They something one could easily get used to?
He has a bump fire stock... which uses the recoil to continuously pull the trigger.
It's basically a legal conversion to autofire that is supported as U.S. legal by the ATF.
Here's a great video of the M10 with a bumpfire stock from Atlanticfirearms.
Watch at the 1:45 mark to see the bumpfire.