For those wondering just how much bigger the GAU-19 Bravo is compared to the modern M134 Delta, this I hope answers said question.

According to Dillon Aero's website, the tubes for the M134D are 22 inches in length from breech face to muzzle, or 558mm while the tubes [Barrels] for General Dynamic's GAU-19 are 36 inches or 914mm.

All of this of course is not including the length of either rotor assembly, or main casing for either machine. And for sake of visual comparison, I've placed the GAU's end plate with bearing assembly directly in line with the M134 above. And if you guys really want another view, I could post a profile with no camera distortion view later.

So practically speaking, I'd no sooner give Yuki an M134 for her maple mayhem, but later in game at say 4th job advancement or higher, then I'd give her the GAU only because of how unwieldy it is, even if placed on an "Aliens SmartGun" like belt / third arm to brace the GAU on!

And now creds of course~

M134 by GE/Dillon/Daycraft
GAU-19 Bravo by General Dynamics
Yuki is  nezumiyuki

And of course all this mentioning of Maple means MapleStory by Wizet and Nexon of Korea