View Full Version : My DIY Ruger SP101 trigger/action job

February 12, 2015, 01:53
For the last few months, my wife has been talking about getting a .22 revolver, which I was all in favor of. A couple of weeks ago, we were at the local Cabela's and found Ruger SP101 with a 4" barrel in the Gun Library that looked brand new. I had her try it on for size, and she really liked the grip, sights, and the weight of the gun, but the trigger pull was REALLY heavy. Long story short, we wound up buying it and taking it home.

It came with the factory box and all the paperwork, owner's manual, locks, and the politically correct fired case. It also had the original price tag in the box from Sportsman's Warehouse from a month earler. We guessed that it had been somebody's Christmas present, and whoever got it didn't like something about it, so right after Christmas they sold or traded it to Cabela's. So it was a month old and still unfired (except for that one round at the factory). Looking it over, I really liked the little gun, except for the trigger pull, which was HORRIBLE!

When I checked it with a Timney gauge, it came out to 14.5 pounds in D/A and 5.5 pounds in S/A. I took it to the range last week to check the sight alignment and try it out. The sights were right on the money, but the trigger was ridiculous. It had one of the stiffest, heaviest triggers I've just about ever encountered, and I knew there was no way my wife would be able to use the gun, because she has arthritis in her hands and has small hands to begin with, so she wouldn't be able to pull the trigger. Which meant she'd never practice with the gun.

So when I got home from the range, I logged on to YouTube and looked for videos on Ruger SP101 trigger jobs and found several videos. After watching a couple of them, I took the SP101 apart. After getting the trigger group out, I depressed the trigger return plunger with a punch and pushed the tiny retaining pin out, then removed the trigger return plunger, spring, and plug from the trigger housing. The videos had shown using a 1/4" drill bit to clean up the trigger return plunger housing by inserting the drill bit and rotating it by hand, so I did that. I found that there was some roughness inside the hole the spring, plunger, and plug fit into, and the drill bit cleaned that up nicely.

I figured that if that helped, doing a little polishing would help more. The trigger return plunger and plug are both hollow, and it turns out that the butt end of a 15/64" drill bit will fit inside them perfectly. So I took the bit and used it for a holder while I polished the plunger and plug with 400, then 600, then 1200 grit wet or dry paper. Then I got a little more creative. I took the drill bit and chucked it into my Ryobi 12V cordless drill, wrapped the drill end of the bit with 1200 wet or dry, and carefully inserted it into the hole that the plunger, spring, and plug live in, and it was a nice snug fit, but not tight. Running the drill at low speed, I polished the inside of the plunger tunnel. Once I had mirror finish, I cleaned the hole with Q-tips, then put some Rem Oil on a clean Q-tip and lightly oiled the hole and put the polished parts back in it and put everything back together.

The trigger was smoother now, but still way too heavy, so I called all the local gun shops, and no one had a spring kit for a 101, so I started looking on line. Intersetingly enough, the lowest price for a Wolff spring kit was to order it from Wolff. So I did. I got a Spring Pak, which consists of three different spring rate mainsprings and one trigger return spring. Wolff's price for that was under ten bucks, and a little over three bucks for mailing it. Total cost came out to $13.78, which I thought was a great bargain. I ordered the kit last Thursday, and it showed up in today's mail.

It took about ten minutes to install it, including tear down, removal of the old springs, installing the new springs, reassembling the gun, and doing a function check. I used the lightest weight spring for the mainspring (the kit has 13, 14, and 15 pound replacement mainsprings; stock spring is 17 pounds) and put the lighter weight trigger return spring in the trigger housing. After the gun was back together, I tried dry firing it, and the trigger pull is MUCH better now. Checking it with the gauge, the D/A pull was just a hair over 11 pounds (roughly 11.25) and the S/A pull was 3.5 pounds. The real test, though, was whether my wife could operate the trigger comfortably. So I took the gun into the living room and had her try it out. With the reworked trigger, she had no problem pulling it in D/A. She still has trouble cocking the hammer to use it S/A, so it'll just be a double action gun when she's shooting it. Putting the new springs in it made a really significant difference in the way the gun feels. The trigger is MUCH easier to use now.

I also have an assortment of springs from Brownell's I picked up a while back, so I'm going to try experimenting with an even lighter trigger return spring and see if I can drop the trigger effort a little more and keep everything functional. Wolff only has one reduced power return spring, and it feel like it's more than enough to return the trigger, so I'm going to play with springs some more and see what happens. Worst case happens, I'll put the Wolff spring back in, since it only takes a few minutes, and best case, the trigger pull will be even lighter yet. I still have to make another range trip to make sure the gun has consistent ignition of primers, but I'm pretty confident that it will.

So for any of you guys who have a Ruger SP101 in any of the calibers they offer, I highly recommend the Wolff Spring Pak. Just make sure you find out when your gun was built, because there's one kit for guns built before 2011, and a different one for guns built in 2011 and afterward. Happy tinkering!

February 23, 2015, 21:36
Damn I want one of those. Your post did not help me man.:D

Dave Dude

February 24, 2015, 07:38
Good work.

You sir, are an inspiration.

Dave O'Neill

March 01, 2015, 19:38
Your right, heckofa gun...just posted one in the MP....hate to get rid of it but it's my safe queen (got 2)...my trigger wasn't bad, Lil heavy but smooth..strongest built 22 for sure...it's a little tank. Great little gun for carrying on the tractor. Might check out the wolf springs..

Timber Wolf
March 01, 2015, 19:56
So, did you determine if ignition is reliable in the re-worked SP? I have one I got last year and it has the worst (heavy) trigger pull of anything I own. I want to love the .22 SP. I have a .357 SP101 that is a favorite, but the .22 is a dog so far. And an expensive dog at that. I would rather shoot my old Taurus .22 pistol.:eek:

March 03, 2015, 17:46
So, did you determine if ignition is reliable in the re-worked SP? I have one I got last year and it has the worst (heavy) trigger pull of anything I own. I want to love the .22 SP. I have a .357 SP101 that is a favorite, but the .22 is a dog so far. And an expensive dog at that. I would rather shoot my old Taurus .22 pistol.:eek:

Yes, I did. Week before last, we had a really nice day when neither the wife nor I had any appointments or meetings scheduled, so we went to the range to let her shoot the 101 and get my RAR Predator's Vortex scope sighted in. We spent about two hours on the range, and shot up a couple of hundred round boxes of CCI Mini-Mags. Had one misfire with the 101, which went off normally the second time she dropped the hammer on it. We're probably going shooting again this week, either tomorrow or Thursday, and run some more rounds through the 101 with different brands of ammo to see what it likes best. If we get any more misfires, I'll try the 14# mainspring, but so far, ignition reliability is about 99.5%.

March 09, 2015, 21:35

When cleaning the SP101, I had the hammer and mainspring out of the gun, but the trigger assembly and cylinder were still in place. Pulling the trigger in D/A mode still seemed a bit stiffer than was absolutely necessary, so I went to the local Tacoma Screw Products store and did some spring shopping. I found a couple of compression springs that would fit in the SP101 trigger assembly. Both of them measured 3/16" in diameter and 1.00" in length.

The stock Ruger trigger return spring is 0.200" in coil diameter and 7/8" in length. Although all three springs were about the same size, the wire diameter of the wire stock used to make the springs were different. The Ruger spring was 0.0345" diameter, the 155-A Tacoma spring was 0.0235" diameter, the 156-A Tacoma spring was 0.0290", and the Wolff reduced power spring wire diameter was 0.0305".

I took the gun apart again and put the 155-A spring in it, then reassembled it. The double action pull was noticeably lighter, but the trigger wouldn't quite reset all the way after a D/A pull. So I took that one out and tried the 156-A spring. That worked, but felt identical to the pull weight with the Wolff spring. Took the gun apart again, pulled the spring out, carefully clamped it in my bench vise, and cut 1/8" of the spring off with a Dremel, then put it back in the gun. Ah, Ha! Now the D/A pull felt lighter.

Just to be sure, I checked it with a trigger pull gauge, and sure enough, the D/A trigger pull was down from 11.25 pounds to 10 pounds even, and the S/A trigger pull is now 2.5 pounds. I doubt very seriously that I'm going to be able to lighten the pull any more and keep everything reliable, so this is a finished project.

So if any of you SP101 fans out there want to improve the trigger, the simple and easy solution is to use a Wolff 13 or 14 pound mainspring, polish the trigger return plug, plunger, and plunger shaft, and use a Tacoma Screw Products 156-A 3/16"x 1.00" compression spring and cut 1/8" off of it. If you don't have a Tacoma Screw Products near you, find a spring 3/16"x 1.00" with a wire diameter of 0.029" (.028" or .027" would probably work too) and cut 1/8" off of it, and you should be in business.