The HK-91 is a great battle rifle, usually quite accurate (it's not a sniper rifle but for it's intended purpose, it's a fine shooter) and almost perfect as big heavy .308's go. Mine would function with any old crappy ammo you could find to stuff into it and it just worked every time. I was able to find some 25 round mags, too.
It is, however, a reloaders nightmare. If you can even find the brass (mine could easily chuck the brass 50'!), it simply and bluntly put, beats hell out of the brass! I've got some old reloads where the case just gave up and split along the flute lines! From just sitting around in a box!
It's also a very dirty shooting rifle and seems to collect more crud with each shot. It will keep shooting, even when incredibly filthy, but I think the best way to clean one that's been shot a bunch is with a bucket of kerosene and a stiff brush!
You did well, getting the 91. It's a great battle rifle that will serve you well for a long, long time to come!
Cheers,
crkckr