I surely am puzzled. :?
Both the LCR front sights that I bought for my .38 LCR were pre-drilled. I put a (pre-drilled) Hi-Viz on first and later replaced it with an XS Standard Dot sight - also pre-drilled. The original sight blade was hollow as were both replacements. The revolver had a post on the barrel shroud, drilled to accept the pin. The replacement sights slipped over this post and the pin was tapped through the sight and post. No drilling was required in either case. I also replaced the the original sight on my .22 LCR with a Hi-Viz. Again, the sight slipped over the post on the barrel shroud. All that was required was a punch and small hammer.