Length Finishing Nail

Having never installed with an air gun, I use standard 6d 2" nails. I'm not sure how 6d translates into gauge. I do know when I pulled off the existing mouldings, the installers also used 2". Cheers, cc

don't know but the nail may need to reach thru various drywall thicknesses into the lumber below, so a couple of sizes may be needed depending on your dimensions.

You want a nail length than guarantees at least least 3/4" penetration into the framing members, but no more than 1". so 7/8" more than the thickness of the molding plus the thickness of the sheathing.

I have been told that to prevent splitting the molding you should dull the point of the nail by tapping it with a hammer. That is supposed to result in pushing the wood fiber through instead of spreading it.