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What is a bump stock and how does it work?

BOSTON — Photos obtained by Boston 25 News show the Las Vegas shooters' guns with 'bump stock' attachments.

But what is a bump stock attachment?

Slide stock or bump stock attachments are legal attachments sold for assault-style rifles -- like the AR-15 -- which can turn a semi-automatic rifle into a fully automatic rifle.

The slide stock uses the rifle's recoil to lift your finger off the trigger and allows it to push right back on as the rifle itself slides forward again.

It's pretty simply visualized and explained in the videos below:

The bump stock, however, is extremely inaccurate as it relies on the motion of the rifle itself to allow for automatic fire. Holding it steady would render the attachment nearly moot.

As Boston 25 security expert Dan Linskey explained on our morning news show, a shooter would have to practice extensively to find the right spot for their finger to make it work.

MORE: Only on Boston 25: Exclusive photos of Las Vegas shooter's guns

ONLY ON BOSTON 25 NEWS: Exclusive photos of Las Vegas shooter's guns
Slideshow | What is a bump stock?

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