The nickname "Pistol" came from how Maravich used to position the basketball near the hip as he started his jump shot, much like an old school western gunslinger. However, your standard revolver holds about six rounds; Pistol Pete had an ammo cache that was only limited by those six personal fouls. If it wasn't for that, Maravich would've easily eclipsed the 70-point mark. We shouldn't get caught up on the "what ifs," though; there's already enough of that in his career. Pete's 68-point classic was his finest moment in unquestionably his greatest season.
Maravich was doing it all, gliding to the hoop and contorting ankles on the way there. He also had quite a few long distance shots, which made him more of a sniper than a pistol. Sniper Pete doesn't have much of a ring to it though. Alliteration always wins.