Howdy,
Sorry, I should have been way more specific. I do the peening with a center punch. Lay the stud on a good hard surface like a vice, or anvil with the head hanging off the side. Just one tap per peen about 90 degrees apart and as close to the head as your center punch allows. Then I do the same thing about an 1/8" further away from the head as the original peens, and 45 degrees offset from the originals. If this doesn't make it feel a lot more sung, you could try repeating with the center punch in the same spots as the first time. If that doesn't snug it up, you'll need something more drastic. Also, pulling the stud into position is better than hammer it in. One thing to remember when you pull it in is to do it in steps. Every time you turn the nut 1 revolution, back it off a 1/4 turn to release the tension if you happen to start it a little crooked. After doing this a few times, it as straight as it'll ever be.
Regards
Gregg