I'd be surprised if any of the optics I listed failed due to recoil. And the all have lifetime warranties, either way. If they can survive on a SCAR-17/SCAR Heavy, they can man a PTR91 just fine. Which is, by the way, just an HK G3 clone. And since when do people serious about shooting balk at spending more on the glass than the gun?
I guess this sub forum really is an alternate reality. I bow out.