I am laying down 5inch wide curupay walnut. As directed on the packaging, I have kept the boards in humidity between 40% and 45% for the past 8 weeks. Now, I am laying the hardwood and when I dial the air pressure back on the nailer, the cleatsls don't go in far enough. When given sufficient air pressure, the cleats go in far enough but the tongue nearly always shows cracking. THe cracks usually extend an inch in either direction from the cleat. Worse than the cracking is actual splitting , when the tonge opens right up.
I have tried 16guage L-cleats and 15.5 guage staples (both at 2 inches length) with similar results.

Am I doomed with this wood? Is it simply too hard to be nailed or stapled? Is this wood harder than oak?
Do I just keep on nailing and ignore the splitting? Does most hardwood have quite a bit of splitting? I am worried that over time, the cracks might extend to the visible surfaces of the boards.

Can I install all the boards manually by drilling pilot holes and then nail them down with a hammer and nail set? If so, what type of nail would be sufficient?

Woodchuck

You might try the 18 gauge nailer.

http://www.nailgundepot.com/shop/catalo ... 27339.html

Is your fastener going in at the exact crease location at the top of the tongue? If not, try shimming up the base of the nailer. If your a hair low, it's enough to cause splitting, you can use duct tape to shim up a little.

THanks for the tips!

Woodchuck