Nail gauge and length for Hardiplank?

[Gator95]

Up until now I'd been hand nailing using 2 1/2" galvanized siding nails. Only had to replace a few pieces of masonite at a time. Will be doing larger area this fall and the idea of hand nailing about a full square does not appeal to me.

What gauge and length are folks having success in using for a pneumatic nailer? Info on Hardiplank webside was confusing and odd at best... 11ga 1 1/2" nails??? WTF.

[just started]

I'm just taking a wild guess here, but could they be talking about roofing nails? I don't think finishing-type nails have enough of a "head" for siding.