How you adjust the sight on an HK G3 or its variants (91, 93, etc) depends on the type of sight. The later ones have a windage screw and a lock down screw. The earlier drum sights, like on my 1970s models, only have a locking screw, which you loosen and then drift by hand. Once you zero these rifles, my experience is that you never have to touch them again - just rotate the drum to match the range.
In the 1970s, when HK first imported their rifles through the office in Alexandria, each one came with a test target. Some were available with the polygonal bore, instead of conventional rifling. I bought both types, and they came with test targets showing groups under .65 MOA.
They are accurate enough that one of my friends used his more daily high power practice, then switched to his M-14 just before the match.
I think any experienced shooter knows what "offhand with a tree for a rest" means: standing with the rifle beside the tree truck.
Any good shot has to be able to hit 10 inches offhand at 400 meters to even place in decent match. Top shooters can place 19 or 20 out of 20 shots offhand into 10 inches at 600 meters with an M-14 using iron sights.
Anyway...back to the comparison with the AR-10.
My first comments were about the current AR-10s, which are mostly heavy rifles for bench play. The military configuration AR-10s are a much more fair comparison in size, weight and function to the HK G3 and FAL, as they were all contemporaries.
I owned an original AR-10 battle rifle, then later a US legal semiauto one. They were solid, and felt a lot like the HK. Since some of the AR-10s from the late 1950s were still seen functioning on television in the Sudan as recently as 5 years ago, with no spare parts, it speaks to the inherent reliability and toughness of the original Stoner design.
