How critical is nail groove in T&G flooring

[Brad_S.]

 I need to do a small run of 500 ft.² of tongue and groove flooring in White Oak.  I already have tongue and groove cutters but they don't have the spur to cut a groove for flooring nails. I hate to spend the extra money for a one time use set of knives. Is that groove critical? I don't want to run flooring and find out I can't get a good tight fit because the nail head is in the way.

[Southside]

My knives create a square tongue, no spot for the nail head, and any I have installed the head ends up counter sunk anyway.