My area requires full round head nails. In So Cal, not only full round head nails are required, but a true code compliant nails is a 16D common nail, which is uncommon for most framing nail guns to shoot.
For example, the vaunted (and excellent) and certainly the gold standard of nail guns in California in general is the NR83a, which shoots a maximum length and diameter nail that is equivalent to only 16 shorts, or sinkers, meaning 3 1/4" long by .131" diameter. However, a true 16D common nail is actually 3 1/2" long by .162" diameter. Very very few nail guns on the market are made to shoot a true 16D common size of nail, yet that is the LA code nail since the Northridge earthquake 30 years ago.
The Hitachi NR90AE can shoot a 3 1/2" nail, but only up to .148" diameter. Essentially, a 12D diameter nail, that is the length of a 16 penny nail. Not to be confused with the NR90AE, is the NR90AC3 (mentioned earlier upthread yesterday by new GJ member "JohnTY"), now discontinued, and it's replacement, now called the NR90AC5. The NR90AC5 is one of the very few framing nail guns capable of shooting a 3 1/2" by .162" true 16D common LA CC Code nail. This nail gun is $349.00.
The less expensive NR90AE, mentioned upthread by GJ member "8 mpg", at around $169, is an entirely different gun altogether, and not in the same league as the NR90AC3 and iterative NR90AC5, which have wholly different cylinders and driver heads than the far more popular NR90AE. The reason that the NR90AE is more popular (and thus has 500 times more reviews) is simply due to the fact that it is cheaper, and unless the buyer completely understands the differences between the lengths and Thickness Diameters of the nails that the code may require for either seismic or hurricane resistance (depending on local), buyers can't see the point in spending more for what on paper appears to be the same thing, offered by the same trusted brand, Hitachi.
So why is the NR83a still more popular among professional framers? Because the air cylinder and head design of the NR83a is yet different still, offering a very fast and extremely durable and reliable refresh rate for rapid firing of nails. In most jurisdictions, the code permits framing a stud to plate joint with 3 x 3.25" x .131" nails in lieu of 2 x 3.50" x .162" nails. So unless an inspector in a local jurisdiction specifically requires the latter nail, shooting three of the former nail per joint will match the calculated structural requirement.
Another favorable point about the NR83A gun, and it's subsequent iterations, including the current NR83A5, the previous NR83A3, and the prior NR83A2... is the top loading steel magazine. Far quicker to load and unload than the back loading aluminum magazines that Hitachi uses in all of the NR90AE and NR90AC guns. The NR83A5 is also twice the price of the NR90AE, and about $20 to $30 less than the NR90AC5.
This is one of those cases where one gets what they pay for.
It is also one of those cases where one may not need to get all that is available... so there is a valid argument for getting a lower cost nail gun for DIY or non professional use.
One thing that hasn't been discussed much in this thread is ammo. The angle of the ammo is often associated with the method of collation. 21 degree strip nails are plastic collated. 33 degree strip nails are paper collated. Coil nails are wire collated. Each has it's advantages and disadvantages.
Plastic collated nails are spaced further apart from each other, which means more reloads, as there are fewer nails per strip. When using plastic collated nails for siding, the "chad", or plastic bits, can get trapped under the head of the nail, leaving unsightly tails for the painting crew to have to putty knife off, if they care enough to. (They don't). The plastic bits can also fly in the face, but that is certainly better than bits of wire flying in the face, and regardless, eye protection should be used at all times.
The advantage of 21 degree plastic collated nails likely outweigh the disadvantages mentioned in the paragraph above, for two simple, but major reasons. First, unlike paper collated nails, which can easily get saturated from condensation or rain or snow, and thus break apart before they are ever able to be loaded into a gun, the plastic collated nails can withstand the flood that Noah sailed his ark through and never fall apart at the seams. Second, plastic collated nails are full round head.
There are some paper collated nails that are also full round head, but there are also clipped head paper collated nails, so extra care must be taken to determine what's in the box. I don't bother with paper collated nails for the first reason alone... I want the strips to stay together... but the second reason is equally important. I know that if I'm ordering a 21 degree box of strip nails, they will be full round head period.
