Happy New year everyone!  I'm building my parents a kitchen table, it's 42" round with 2 12" leaves.  6/4 red oak finished to about 1 1/4" thick.  I recently purchased a domino 500, and love it.  It's changed my woodworking life.  Anyway, I was wondering what you guys think about using dominos instead of the traditional pins used to line up leaves.  I assume I'd either need to sand a tad off the part of the domino that sticks out or make the mating mortise hole just a hair thicker since in my short experience it takes some effort (even a rubber mallet)  to join two domino'd boards.  I've already purchased the brass hardware pins, but it seems like it would be a lot easier to use dominos if you guys think they'll work.  Any thoughts, ideas or suggestions?

I think it's a great idea, but I would mortise both sides on the narrowest setting. I would glue the domino in one leaf and gently sand the edges of the other end to ease entry. If alignment proves too difficult, then at least keep one pair of mortises on the narrowest setting or the leaves will not line up properly.

I would only use the narrowest on 1 domino per leaf. After all, how is any different from domino-ing anything else, sans glue?

I assume the pins you have are the ones that have a pin on one side and the sleeve on the other.  I wouldn't attempt the pins unless I had a good dowel jig like the DowelMax or the Jessem to get the holes just right.

And you've already got a Domino.  So I agree with the others, the domino would do this job well.  You can go all the way up to 10mm if you want.  You could mill your own tenons out of scrap from the tabletop or use any species.

And if registration isn't perfect you can make it perfect by fine tuning the tenon.  You couldn't do that with anything else.