First, want to give a huge shoutout to u/TourettesYapper for posting his guide and a link to the rear sight. I ordered this one last week...

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https://www.amazon.com/gp/product/B095WBLX2N

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And it came in this afternoon. Had it disassembled in about 5 minutes, and reassembled in about the same amount of time. The spring that holds the little ball bearing in the receiver was too short to use, so I cut down a spare detent spring I had. The roll pin that holds the big spring in is also too small, so I'll replace that eventually, but it holds under tension right now. For anyone wanting a cheap option, who isn't concerned about shooting beyond 600 yards, this works great.