For practice ammo - 62 grain or higher Wolf
- Don't worry about this ammo. A lot of people will say that its crap and will be hard on your rifle. I've shot thousands and thousands of rounds of Wolf and never had any problems through a variety of AR15's and AK47's. It's not high quality by any means, but it works and it's cheap.
For home defense ammo - 75 grain Hornady TAP 5.56
- All the Hornady TAP stuff is good, but the actual TAP 5.56 will give you the best velocity/ballistics over the TAP .223 which isn't loaded as hot. Actually finding the TAP 5.56 load will be more difficult though as it's not sold directly to civilians...but you can find it if you look and it IS legal to own and use. It will be brass cased and come in a red box. Just look for TAP 5.56 and not TAP .223...but again, all Hornady's TAP ammo is very good so its always a top choice.
Since the 416/MR556 has a 1/7 twist barrel, I would use 62 grain and higher as the tighter rifling will allow you to stabilize the heavier bullets.