Of course, this will vary depending on the nail manufacturer, but the following website will give you a pretty good estimate: https://www.treeisland.com/sites/default/files/documents/brochures-spec-sheets/Average%20nails%20per%20pound.pdf
I'm a homeowner and used a DeWalt and a Metabo palm nailer. Works great. Could have used a hammer -- but why? Would have likely bent a few with the hammer in the tight quarters. The nails do bite into the wood. Try pulling and moving a hanger after install. You see they bite quite well.
The nails are 10 penny by 1-1/2". A #8 screw 1-1/2" could be used instead of the nail. Look for pan head instead of flat head (like drywall or deck screws). The screw heads will lay flat against the bracket.
well the picture says "QTY:600" so I'm gonna assume roughly that.
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