S&W J-frame

[jeepnuts]

I’m no gunsmith but I have a 442 we can open up and compare side by side if you’re ever in Gwinnett on a weekend

 

[CTS Tactical]

Looks like a shadow to me.

 

[AKinnard]

Are you asking about the piece the screwdriver is on? If so that’s part of the cylinder release

 

[flyingk9]

Hard to tell from pics, but does the hand move freely through the window and engage the star on the extractor? Looks like it isn't from the last pic.