Ruger flattens the front lug pocket in the barrel, I have done this on several, it works great, just go slow & test fit before peening it moreThe barrel has some play in the frame of my MkII.
What's the best way to tighten the barrel fit in the frame?
do a seach for loose barrel here, or the 22/45 section, there is a photo of where to peen the barrel