Reb., It will hold up to 5.56/.223 or whatever else you want to use it on. I took a PROSTAFF 3-9 BDC that I have, mounted it on my Brown Precision .375 H&H and talked 3 buddies into shooting 3 20 round boxes of shells. Absolutely zero issues with the scope. My buddies shoulders were a tad tweaked, but the scope functioned as I knew it would.
I am currently using 2 PROSTAFF 3-12 BDC's on my .308 and my son's .308 bolt avtion rifle.
Drop me a note with any questions.
Here's a pic of my father in law with my .308 and PROSTAFF scope.
http://i1216.photobucket.com/albums/...aveanddeer.jpg