AQ - In my experience a 1-9 will do OK up to 69 Sierra MK's. If its a 20" barrel, it might also stabilize 77 MK's. I don't shoot any surplus stuff, so I don't really know whats available. If it has heavier bullets, just don't buy a ton until you try it out.
I took my M4 to the range last week. I had 11 orphan brass from a lot laying around, so i loaded up some 57 gr. Hp's that I swaged from 22 brass. The gun functioned great for all 11 shots, which was my biggest worry. I got it on paper at 50 yds, and plan to go back when I load up some more ammo. I just shot prone with no sling but got some decent accuracy IMO.