Apply a thin coat of oil to all surfaces. I prefer Slip 2000. At the risk of opening a debate, I think good synthetic 5W-30 motor oil works well.
Reassembly is basically the reverse of disassembly. If the trigger guard assembly refuses to swing back into the frame, the transfer bar or pawl may need to be repositioned, the trigger pivot pin may be sticking out or the cylinder latch may not be fully inserted. Be careful not to pinch yourself between the trigger guard housing and the frame.
While holding the trigger back, insert the hammer into the frame. Insert the hammer shims. Insert the hammer pivot pin. You may need to use a paper clip or feeler gauge to align the hammer shims before inserting the pivot pin.
With the trigger forward, insert the hammer strut and mainspring. Be sure not to put the strut in backward. Pull the trigger half way and remove the paper clip or pin from the hammer strut.
Test your revolver for proper operation. The trigger pull should be smoother and lighter.
Can I use emery cloth instead of sandpaper?
Where can I find 1000 - 2000 grit sandpaper?
You can find it at auto parts stores and in the auto parts section of most big retail stores (like Wal-Mart). Some home improvement stores will have it.
Can I use this guide for my Ruger Security Six or other revolvers?
This guide was written specifically for the SP-101. You can read through this guide to get a feel for the process, but there are some differences between various Ruger models. I don't recommend using this guide for other models.
If you break something, replacement parts can be ordered from www.gunpartscorp.com.
Here you can watch a simple animation of the Ruger SP101 trigger pull sequence.
High quality stainless steel shims can be bought from Lance at TriggerShims.com. He also has an eBay store under the seller name "Michigan Center Outdoors". Lance produces all his shims by hand.
rugerforum.net is a great forum full of helpful information and friendly people.
This guide was inspired by my personal experience, "Iowegan's Book of Knowledge", posts from the rugerforum.net forum, the Ruger SP-101 owners manual and various other sources.