I believe I heard that a particular SWAT department in California has M16 in burst

I'm sure there are plenty of Police Departments all over the USA that still have the M16A2 in it's original select fire configuration.

Does LAPD still use .243 bolt guns?

I'm fairly certain that they are now using customized Remington 700 rifles in .308, but I might be thinking of L.A. County instead.

I'd be kind of surprised if any of them used M16s at all, considering the M16 is too long for SWAT uses.

I think they use them for sniping. Which is pretty weird.

The M16 is roughly the length of most Assault Rifles.

Specialized DMR versions (Mark 12 Mod 0/1, SAM-R, SDM-R) are used by the military, so I see no reason why a SWAT, HRT, or SRT unit couldn't use one for the close-in marksman role.

Right, but nobody uses full-size assault rifles for CQB anymore...that's what carbines are for.

The marksman idea makes more sense, I guess, but even so, there are better AR platforms for DMR than the standard M16.

I think I'd go with the 4506. It's a classic. The only problem is it isn't made anymore :(. My second choice is the Beretta 92FS. I also think the Kimber is excellent, but obviously, I'd only use it if I were SWAT.