To what extent does AFQT correlate with IQ? Wikipedia has a pretty non-informative page as to the nature of the (US) Armed Forces Qualification Test (AFQT) as it mostly talks of results ranges etc. What I could descipher from there is it that it has three (or maybe four, depending on how one counts) [sub]parts, 


Arithmetic Reasoning (AR) – 30 questions in 36 minutes
Mathematics Knowledge (MK) – 25 questions in 24 minutes
Verbal Expression (VE)= (WK)+(PC)


Word Knowledge (WK) – 35 questions in 11 minutes
Paragraph Comprehension (PC) – 11 questions in 22 minutes



and


  The formula for computing an AFQT score is: AR + MK + (2 x VE).


That sounds a bit like SAT... and a quick search found one paper that talks of "cognitive skills as measured by the AFQT". (SAT is pretty well correlated with IQ.) So, to what extent does AFQT correlate to more traditional IQ [sub-]scores?
An answer is found in an official memo, albeit from 1980, where


the correlation of AFQT with WAIS (no version specified) was stated as 0.8 based on a Army "fact sheet" from 1965; the details of the comparative test could not be found
an Air Force comparison found (in 1974) that the correlation (again with WAIS, no version specified) for white enlistees was (again) 0.8 but 0.77 for black enlistees.


(This ~0.8 is actually about the same as the correlation of IQ tests with SAT.) I don't know if the AFQT is still the same as back then.

A official-looking 2006 concordance/translation table of AFQT score with SAT scores can also be found, although it's rather summary; it doesn't mention a correlation coefficient.