Hi, I'm a first time poster getting ready to do my first hardwood floor project.

I'm getting ready to lay about 350 sq ft of 3/4" Oak flooring. I have read on this forum and elsewhere on the web of many people using the Harbor Freight model 99640 floor nailer with 3/4" flooring. However the nailer states that it is for 25/32" floor. I have placed the nailer on a piece of 3/4" and I can tell that it doesn't fit perfectly over the tongue of the wood and needs an extra little nudge to ride over it. Is this acceptable? If not can I shim the pad with a piece of cardboard?

Thanks in advance for any help.

Take a small piece of the flooring and use the nailer to see where the nail ends up. If it shoots in the angled corner where the top of the tongue turns and goes vertically towards the ceiling it is shooting in the right place. That's an easy way to test it on a small piece of flooring you can always pull it up if you only put one nail in.

Thanks for the reply Justin. So is it alright to shim it with a piece of cardboard? I measured a piece and it was almost exactly 1/32". I will definitely be doing some tests before I start nailing in earnest. Based on what I've read on this forum I will be using Bostich 2" 15.5 gauge 1/2 inch crown staples. My subfloor is 3/4" OSB.

I guess my biggest question is why does Harbor Freight sell a 25/32" nailer. I searched the internet and couldn't find anyone selling flooring at that thickness.

Many of the older well established unfinished flooring mills make the floor at 25/32 inches.
The most common explanation I have gotten is so that the end user (you) will have a 3/4 inch floor after it is sanded and finished. Make sense? I guess.
What I don't understand in your case is how that would impact on the nailer you wish to use.
My guys install both pre-finished (3/4) and unfinished (25/32) without any mods needed for their equipment. However, shimming the base plate should not be a problem. A couple (or few) layers of masking tape will shift the penetration location upwards if that is what is needed. However, I believe that if ANY adjustment is needed it would be the opposite and you will need to lower the entry point. For that, some mod to the plate itself will be needed.

Dennis, thanks for the explanation of the 25/32 flooring. About the shimming of the floor nailer: I was under the impression that a thinner board, 24/32 instead of 25/32 would require an insertion point that was closer to the top of the board, thus requiring additional thickness to the base plate to raise the tool. Anyway, I'll be doing some testing before I start.

Regardless of the overall thickness of the wood, the key factor is the staple should enter the board exactly at the juncture of the tongue protrusion and the upper portion of the board. That area is termed the nailing pocket. The M111 FS has been used to nail down many different thicknesses of flooring; 7/16", 1/2", 9/16", 5/8", 11/16", 3/4" and 25/32". I guess it could even by used for 33/32" gym flooring with the right base plate. Test fire until the staple seats right where the tongue protrudes from the board. Not into the tongue but directly above it. On 3/4" NOFMA solid flooring, there's a nailing pocket there. The staple should just sit flush with the wood. Not go in too far and stick out either. The "bumper nose" at the front of the nailer/stapler should fit over the tongue and engage that instead of the edge of the board. That's important or the edges will get mashed.