Accessories

Do you really need it?
I've had this gun for a good few years but about to swap it for the nr83a2
Unless you have a pacific need to shoot bigger nails buy the nr83a2. Its cheaper lighter and will shoot into anything your likely to come across.
8's weren't a problem to start off with but now jam regularly and drive me mad hence the swap.

The Nailer Would Not Feed Properly
This nailer would not feed 16d nails reliably so had to return it. I called Hitachi and they told me the feeder on this unit is larger to accomodate full size 3 1/2 inch nails strips. Since I am using 3 1/4 inch 16d and 8d most of the time, they recommended I buy the NR83AC nailer instead. I wish this information had been in the product details.

The best for 3" + nails but bad for the 8d's
I am convinced that there is not a better gun made that can shoot a big nail through the tuffest wood! I have bought 2 of these guns in the last 3 years to replace senco's and they are simply the best...EXCEPT They jam when using 8d's (2-3/8" nails). What happens is the nail track is too big for the 8d's and eventually they ride up on each other and don't feed properly after you have shot a couple boxes of them. This is a common problem with most framing guns because of the different diameter nails they shoot. If you only feed it one rack of 8d nails at a time (it holds 2) then the jamming is not so bad. The NR83 shoots 8d's better but it doesn't have the punch of the NR90, nothing does. If you plan on doing some heavy duty framing get the NR90. If you are an occasional or light duty user or a hobiest get the NR83 but get a Hitachi.

Some comments on the negatives
I own a NR90AC2,same gun but does not have a lever select on the trigger:
On the 8d nail issue,in that size, I shoot ORCO brand,made in USA, in the gun, 2 3/8" ring shank Egalv. and never had a jam. Cheap off brand nails or the wrong angle=jams. 6d(2") nails are not for this gun. I always shoot ringshank into sheet goods b/c of the better grip. 6d's are not code here in CA anyway.
The single fire AC2 issue, you need to change out the trigger, the included one is a NOT a single fire(sequential) and will easily double fire, it is a contact fire(bump) type. Change out the trigger and you can not double fire as was said. AC3 has a lever to change it, AC2 you have to change out the whole trigger assembly.
This is an excellent gun ,drives into anything wood,but you have to use good quality nails and be aware of the trigger b/c it has a lot of power. I never like bump fire, a safety hazard,waste of nails,inconsistent depths.

Doesn't shoot all nails
We Purchased the NR90HitachiAC3 because we liked the Hitachi83 that we had for years, but didn't have an adjustment for the nail depth. They advertise that it shoots nails from 8's to 16's. The bigger nails, it shoots fine with not much kick back. Doesn't jam on them. The 8's are a nightmare. That is the main reason that we bought the gun for the 8's as we wanted to be able to adjust the depth while doing the sheathing for all the required engineering. The nails either jam or the slide slips by the nails. Not just a few times, but every time.
If you are buying this gun for shooting 10's or 16's then it is a fine gun. If you want it for nailing the shear walls with 8d's... forget it, it is a waste of time and money.