I would strongly recommend you replace the hammer/trigger/disconnector springs. And a new recoil spring is a good idea while you're at it.

I always start with a fresh set of springs, and replace them regularly (every 10k rounds for 5.56, 5k rounds for 9mm or 7.62x39). It's like changing the oil on a car engine. Springs cushion the entire action –– they keep the hammer from impacting the disconnector and transmitting that force to the trigger, and thus to the trigger and hammer pin holes in the walls of the aluminum receiver. Replacing those three springs will cost ya $10 total and could save you from expensive receiver repairs. Weak or unknown-mileage springs can allow your receiver to be damaged.

I run my '16s on the wet side –– they do get gunked up a little more often that way, but it keeps the ROF stable. Dry, or close to dry, and the gunk buildup can have your rpms wobbling all over the place. Just not so wet that you end up with messy shooting glasses.

Considering that the last transferable M16 was manufactured prior to May 19, 1986, IMHO it's not a "new" weapon –– and even if it is unfired, after 23 years of storage I would change the springs anyway.

I would inspect them for wear –– bright metal or flattened contact areas. If your '16 is a factory Colt, they should be milspec, and if they don't show wear, I wouldn't worry about it. If it's a conversion you probably won't know the source of the parts, so it may be best to swap 'em out.

OTOH ... when you first take delivery, you're gonna want to shoot it right away, and often, correct? So maybe you should buy a complete set from SAW to keep as spares if everything runs fine .... or to swap in immediately if there are any issues. It's always good to have spares available. And there's nothing worse that being at the range with a non-functioning MG and discovering you need to order parts from across the country.