The problems with finding carbons are well known, and they are generally not allowed at many outdoor clubs/shoots. Fat carbons are good for indoors being relatively cheap so easily replaced and good linecutters. Outdoors A/C arrows are thinner - less wind effects, similar weight per inch - good sight marks and straight to good standards. Thin carbos are available and have most of the advantages of A/C but difficult to find, plus 1/2 price of A/C.
try this link for a detail on arrows - download a catalog and tuning guide
http://www.eastonarchery.com/