SP101/GP100 Tuning
Here is information from a post over at Ruger Forum by a retired gunsmith on polishing. I would post a link but it appears the information is no longer available. This was posted by user Iowegan(he also posts on the S&W Forum under I believe SWIowegan):
Here's the instructions for a SP-101 Action Job. The same procedure will work for a GP-100 or a Super Redhawk however the part numbers will be different.
You can refer to the SP-100 schematic on Brownell's web site, I'll include the schematic numbers for parts as I go.
http://www.brownells.com/aspx/NS/schematics/schemmfg.aspx?schemid=31&m=13&mn=Ruger®&model=SP101+ It's easier to print it than try to switch from screen to screen.
Disassembly:
1. Remove the grips. Note a small pin will fall out (8).
2. Cock the hammer and insert the small pin (8) in the hammer strut hole then slowly lower the hammer and remove the hammer strut assembly (23,28,29). If you don't have the pin, a paper clip will do.
3. Pull the trigger all the way back then push the hammer pivot pin out (22) and lift the hammer (61) out.
4. Locate the trigger guard latch (42). It is a spring-loaded plunger that holds the trigger assembly in and is located about 1/2" down from the top of the grip frame channel, inside the grip frame. Use a screwdriver to push the latch pin forward while pulling down on the trigger guard. The complete trigger assembly will come out as a unit.
5. Set the gun aside and we'll work on the trigger assembly. Pull the trigger about a 1/2" and remove the transfer bar (41).
6. The next step requires attention because a spring-loaded plunger will launch. Put the trigger assembly in a plastic bag then hold the trigger back while pulling the pawl (30) to the right. The spring and plunger (3 & 4) will pop out.
7. Locate the small retaining pin (21) at the upper corner of the frame latch, just above the trigger guard latch pin. Push the trigger guard latch in (42). Use a paper clip to push the retaining pin (21) out. Note: schematic shows two #21, you want the one by the trigger assembly.
8. Pull the trigger guard latch out of the hole. Use your paper clip in the front of the hole to push and remove the trigger guard latch spring (43) and trigger link plunger (46).
10. Pull the trigger back then use your paper clip to push the trigger pin (64) out then lift the trigger out.
11. Remove the trigger plunger (47) from the trigger.
12. Back to the plastic bag for another launching part. Pull the cylinder latch (5) to the right and another spring and plunger (7 & 31) will pop out. Note: this spring and plunger look like the one from the pawl only longer.
Now let the polishing began:
13. The trigger assembly is stripped ready to do some work. Start by using a jeweler's file to "dehorn" any galls or rough spots you can see or feel on the trigger housing (63). The inside walls of the trigger channel and the front latch lip in particular.
14. I lied! you will need one more tool for the next task. Use a 13/64" drill bit and insert it inside the hole for the trigger guard latch. You don't want to drill the hole any deeper, just hand twist the bit to remove any galls. This hole is usually rough and accounts for a gritty trigger feel when the plunger moves over the rough spots. Sometimes the holes are so bad that you can't hand turn the bit. I have an old drill chuck off a dead drill the works really great for jobs like this.
15. Look at the trigger (62) and locate the rounded cam on top and the SA sear at the end of the cam. Buff the cam and sear nice and smooth without removing metal. I use a buffing wheel on my bench grinder or a Dremmel tool with a felt wheel. The smoothness of the cam and SA sear will make a big difference in both DA and SA trigger pull. Make sure you don't change the sear angle or remove much metal, only enough to make it smooth. Dehorn any sharp edges on the sides of the trigger.
16. Locate the trigger plunger (47) and find the 45 degree angle at one end. This surface must be very smooth in order for the trigger to reset. Buff it without removing metal. Dehorn the sides.
17. Locate the cylinder latch (5) and look for the surface on the bottom of the part that looks like a backwards "L". The surface parallel to the hole must be smooth. This part is often very rough with machine marks. It must be smooth to get a trigger reset. Dress the surface and buff it. Buff the rounded area of the latch that locks into the cylinder. Smooth and shiny will reduce cylinder drag lines.
18. Locate the transfer bar (41) and dehorn it.
19. Locate the pawl (30) and dehorn it then buff the tip, especially the left corner. This part contacts the ratchets and will rasp in DA if not smooth.
20. OK, we're ready to reassemble the trigger group. Start by inserting the long spring plunger (7 & 31) into the trigger guard (63). Slide the cylinder stop (5) round end up, on the shaft until it touches the plunger. Back to the plastic bag. Use a tool to push the plunger in while sliding the cylinder stop in place. Out of the bag.
21. Place the trigger plunger (47) back in the trigger. The nose goes in the slot first, between the stud and base. Make sure it is not upside down (see schematic).
22. Set the trigger in the trigger guard making sure the trigger link (44) goes in the latch hole. Align the holes and insert the trigger pin (64). You may have to insert a paper clip in the back of the plunger hole to position the trigger link.
23. The trigger should swing freely in the trigger guard. If not, disassemble, isolate the bind and file it down.
24. Pull the trigger back and insert the spring plunger (3 & 4) in the hole. Back to the plastic bag and slide the pawl shaft part way in the hole. Use a tool to push the plunger down while sliding the pawl (30) into position.
25. Insert the trigger link plunger (46) into the plunger hole, cupped end first. Insert your reduced power Wolff trigger spring. Use the heaviest one in the kit.
26. Insert the trigger guard latch (42), flat side up then push it in while inserting the lock pin (21).
26. Pull the trigger part way back and insert the transfer bar (41) into the trigger.
27. Set the trigger group aside for now and go back to the gun. Press the cylinder release and swing the cylinder out. Pull the cylinder assembly forward to remove it from the frame.
28. Hold the cylinder so the ratchets are up. Inspect each ratchet for galls and rough spots. Use a jeweler's file to dress smooth. You are concerned with the portion of the ratchet where you can see a slight angle. This angle's vertical surface is where the pawl drags and must be smooth. Don't take any more metal off than is absolutely necessary else timing will be affected.
29. Look inside the frame and inspect for galls or nasty spots. Do not dress the outer surface or it will not mate properly with the trigger group. It's not unusual to find splinters of stainless material so clean them out and dehorn.
30. Locate the hammer and use a paper clip to push out the hammer dog pivot pin (21), the one in the schematic by the hammer. There is a spring plunger under the hammer dog but it shouldn't launch.
31. Inspect the hammer dog (no number) and dehorn it. Buff the bottom rear surface (long end). This surface mates with the DA cam and must be smooth.
32. Inspect the sear notch at the end of the hammer extension. This is the SA sear and must be smooth. Dress if necessary but do not remove any more material than you absolutely have to make it smooth.
33. Install the hammer dog, long end down and insert the hammer dog pivot pin (21). Test the hammer dog for free springy movement.
34. Locate the hammer strut assembly. Draw a sketch of how the seat is on the strut. If you reassemble upside down or backwards, it won't work. Place the ball end of the hammer strut (23) vertically in a vise, up to the spring. Use a kitchen fork and force the tines between the mainspring (28) and the mainspring seat (29). Compress the spring by pushing the fork down with one thumb on the ends of the fork tines and the handle in the other hand. Compress until you can pull the pin out of the strut. Be careful! Ease the mainspring and seat off of the strut.
35. Use your file and dress the spring strut. All edges where the spring rides must be smooth or DA pull will feel gritty.
36. Install the heaviest of the new Wolff hammer springs. With the strut in the vise as before, use your fork to compress the spring then slide the seat on as per your sketch. Insert the pin (8) to retain the assembly. Dress the strut's ball tip and make sure there are no rough or sharp areas.
37. You are now ready to reassemble the gun. Start by installing the cylinder assembly in the frame and snap the cylinder shut.
38. Lay the trigger assembly in place and hook the nosepiece into the frame. Hold the muzzle up to get the transfer bar back, then muzzle down and snap the trigger assembly into the frame. If it doesn't go in easily, don't force it. The pawl and/or the transfer bar may not be in the proper position. Pulling the trigger slightly may help.
39. Pull the trigger all the way back and set the hammer (61) in position. Insert the hammer pivot pin (22).
40. With the hammer forward, muzzle down, insert the ball tip end of the strut, flat edge up, into the hammer recess until the seat is positioned over the lugs. Cock the hammer and pull the pin out. Replace the grips and you're done.
As noted by another poster above what spring weights will work depend upon several factors. Often to get a brisk trigger return the 10 lb. spring might need to be retained. I don't have a rimfire .22 so cannot comment but on my Jacobson tuned .357 the 9 lb. mainspring works without misfires but headspace is near minimum. Other factors that affect what will work are the amount of endshake and firing pin protrusion (some Rugers are noted as having less than desired). Either can be remedied. Thus, to see what works you will have to try the various weights
