Here are the HK91 bolt head differences for the polygonal v. standard. Tony
AGG Staff member Feedback: 8 / 0 / 0 Joined Nov 11, 2020 Posts 6,611 Location Alabama Feb 12, 2023 #1 Here are the HK91 bolt head differences for the polygonal v. standard. Tony Attachments HK91 Bolt Heads.jpg 113.2 KB · Views: 9 HK91 Polygonal v. Standard Bolt Head.JPG 147.7 KB · Views: 9