Ok, I'm going to change out the MSH on my 1911.  What all is involved in this process?  Just the one retaining pin?  Hammer cocked or released?  Thanks.

Do you have a Springy with ILS?

I just changed one on a Kimber Pro Carry II. I ran into some difficulty this time that I had never experienced before. Go to the gunsmithing section and check the threads from a few days ago where I'm asking for help.

This one is a S&W, full size.  

Same procedure for your Smith.

I've done four of these, but as I found out, I don't know as much as I thought I did. I'm sure one of the guys that helped me will be along shortly, and they know alot more than I do about 1911s.

One of those jobs where you could use an extra hand or two, but overall,pretty simple. Hammer down, push out the MSH retaining pin. MSH will slide right out. There is a small pin near the top right of the checkered surface of the MSH. Be careful pushing that out,as it is under spring pressure. Removing this pin allows you to remove the internals of the MSH. Move the internals to the new MSH, and push down on the top spring cup with a punch, and hold it down(tricky) while you replace the pin. Slide the assembled MSH into the frame,making sure that the end of the hammer spur sits in the dimple on the top cup. Re-insert retaining pin----voila!