I've put about 2k rounds through my PTR so far. The setup is a standard length PTR with Factory HK wide forend w/ factory HK bipod, Springfield trigger job, B&T mount, Sightron SII mil dot 4-16X42 scope, and a Top Notch clone MSG-90 stock. It has been great, but it really surprised me today.
I wanted to get it zeroed at 200m. I figured it would be much harder to zero it 200m than 100m because every error I make will open up the group twice as much. So I cheated and bought this rest www.sportsmansguide.com/cb/cb.asp?a=213584. I know it's not the best but it worked well.
Anyways after about 15 min of messing with it I got her zeroed in perfectly (well for me). Anyways I was very surprised just how accurate PTR's can be. I remember alot of people claiming a HK91 is a 3-4moa rifle. I guess the heavy barrel helps because I shot 4 three shot groups after I had it zeroed and none of them were more than 2.25" at 200 meters using South African Surplus ammo. I saved the best target:
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Anyways I just was just amazed and wanted to share. I will fully admit that I'm not the best shot otherwise I wouldn't have needed the rest.