What does a spade grip do?
 

I feel like I should know, but I don't.

What are the reasons for using a spade grip on a mounted machine gun?

So you can swivel it at greater angles, but still have control. For example, if you are riding in a helicopter and you have to shoot some thing almost directly below you with a stocked MG, the stock will get in the way

Ooooh. That makes sense!
How about another question.
How do you shoot a spade MG? Is there a button or something?

Pretty much, the technical term is a butterfly trigger. We even have a kit to convert a C6 (FN MAG) to spade grips.

Really? I was just guessing

The v-shaped mechanism is the trigger.

http://www.projectguns.com/sitebuild...g1-600x503.jpg

Dang that looks kind of weird.

No, THIS is weird:

http://www.dsarms.com/images/KNSARSG.gif

Yup the AR15 is probably never going to run out of any accessory, that’s for sure.

Spade trigger and a crossbow upper... What's next?