The AC130 was a modified C130 (Hercules) cargo plane. The A stands for attack, the C stands for cargo and the 130 is the aircraft designation. The AC130 spectra or spooky was commonly refereed to as "Puff the magic dragon" There are different types of AC130's depending on what guns they carry. "Puff the Magic Dragon" carries 6 .308 caliber miniguns while the Spectres carry two miniguns 2 40mm cannons and a 80mm howitzer.
No such thing. You can have small caliber but not low caliber.
Some guns yes, but most guns would require gunsmithing to change caliber.
Pellet guns tend to come in two standard caliber sizes. The first smaller caliber is the most common for pellets guns and is .177 caliber. The second is .22 caliber that can be found on some higher powered pellet gun models.
7.62 mm (or 30 caliber) and 5.56 mm (or 223 caliber) are common rifle cartridges. Pistols, machine guns, and artillery will of course be different from these.
The AC-130C130U aircraft has 25mm Gatling guns, a 40mm Bofors cannon, and a 105 mm artillery piece. Good article for you- http://en.wikipedia.org/wiki/Lockheed_AC-130
The caliber
you press triangle on ps3 and Y on Xbox 360 !
the ac130 already has infinite ammo.
.68. Almost all guns are this caliber.
The 308 caliber guns are more expensive than 5.56 assault rifles.
You get it by using the AC130 killstreak 10 or so times.