The only thing that HTC could really do to code this would be to have a string of X number of rounds fired per pull of the trigger and then a pause for the "reload". For instance, iirc the
magazines (dont call them "clips", it only shows your lack of understanding in proper terminology

) that fed the Wirblewind has a 10 round capacity, so if HTC wanted to model the reload delay in some manner they could do a 40 round burst followed by a 1 or 2 second delay. Without looking it up, I think the Ostwind had an 8 round magazine but since the rate of fire was so much slower than the Wirblewind the loader(s) shouldnt have much of an issue keeping it fed.
With the M16, the length of the belts in the drums are 150 rounds, iirc, so if HTC wanted to model the reload there it would be more difficult because the burst would have to be 600 rounds long before modeling the pause for the reload would be a bit more of a stretch. It might be best to leave the M16 alone.
EDIT: With the reduction of the general aircraft to gv icon range, now may be the best time to implement the reload time for the Wirblewind seeing as how the AA will not be detected so soon.