Ruger SP101 Problem

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dfletcher

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Sep 14, 2006
Messages
921
I know my way around most revolvers very well - Colts old & new, S&W, Dan Wesson and Taurus, etc. Rugers, am OK but not 100%. Have an issue with a newer SP101.

The DA pull had a little hitch in it's transition from the 1st DA stage to the 2nd stage. The lower DA lifter was a tad low so instead of pushing up the hammer smoothly there was a slight hesitation. Found a trigger (trigger only, not the full assembly) on EBay and it dropped in fine. Did a basic function check without the hammer in and everything worked fine. Dropped in the hammer - nice and smooth in DA mode, the way it should be. SA - no problem. However with the hammer in the cylinder bolt doesn't reset. Resets perfect with the hammer out, no go with the hammer in. Has me a bit stumped.

When the gun fails to function the trigger moves back about 1/4". I swing open the cylinder, press down on the top of the cylinder latch (bolt) and it "clicks" back into place. Until then, the front of the "trigger plunger" isn't engaging the cylinder latch (bolt) by riding over and clicking back into place. Again, this happens only when the hammer is installed. With the trigger unit only it functions perfectly.

https://www.gunpartscorp.com/gun-manufacturer/ruger/revolvers-ruger/sp101

All springs are full power. The transfer bar isn't catching on the rear of the firing pin.

Am I correct that the "parrot's beak" of the trigger plunger is fitted to engage the cylinder latch (bolt) and that's the part to be worked on? I'm aware that fitting incorrectly will cause the bolt to not drop before the cylinder starts to rotate.

If the above is accurate, any advice or tips on how to fit the trigger plunger and cylinder bolt? I've ordered two of each from Numrich as a "just in case".

I know I can return the gun to Ruger with original trigger installed however I expect they'll just return it to me as "good enough" since that's how it left the factory. So it's either fix it myself or sell it.
 

Thel

Blackhawk
Joined
Jun 22, 2010
Messages
615
Don't know about the plunger and cyl. bolt. The original problem with the hitch sounds like where the cocking of the hammer is handed off to the double action sear from the hammer dog riding on the top of the trigger shelf. A very slight filing can relieve that situation. There is a post on the other Ruger board about this but I don't know if we are allowed to give a link. Other than that I would look inside the new trigger and compare to the original to see if there are any burrs and such that may explain the cause of the problem. It sounds like the trigger plunger is trapped underneath the cylinder latch so does not reset so it can release the cylinder latch.
 

hittman

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Jan 16, 2008
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9,010
I don’t know the answer to your questions but believe the mother ship works on them for free ….. just sayin’.
 

Captain America

Buckeye
Joined
Dec 17, 2015
Messages
1,956
I had a friend bring one by with a very similar problem after he disassembled it. He deformed the tiny spring in the trigger plunger, I had some because the good people at Ruger sent me five for free after I launched one through a hole in the fabric of the space/time continuum. It was an easy fix once I found it.
 

dfletcher

Blackhawk
Joined
Sep 14, 2006
Messages
921
Thel said:
Don't know about the plunger and cyl. bolt. The original problem with the hitch sounds like where the cocking of the hammer is handed off to the double action sear from the hammer dog riding on the top of the trigger shelf. A very slight filing can relieve that situation. There is a post on the other Ruger board about this but I don't know if we are allowed to give a link. Other than that I would look inside the new trigger and compare to the original to see if there are any burrs and such that may explain the cause of the problem. It sounds like the trigger plunger is trapped underneath the cylinder latch so does not reset so it can release the cylinder latch.

Correct re the original "problem" and my feeling is the misfitting was one of too much already removed during factory fitting. The correction, were Ruger agreeable to doing so, would be a new trigger. The one I installed to correct really shows the difference between how it is (with the factory fitted) and how it should be. Since Ruger left this one out of the factory with the hitch my concern is they'll deem it OK if I send it back.

What has me stumped is that the action works fine without the hammer installed. Through some scribing and testing I've found the trigger doesn't return to the same position with the hammer installed as it does without. 99.99% the same, but the underside of the upper DA sear lifter rests on the top of the single action sear notch dog leg. Resting on it keeps the trigger just a hair higher than with the trigger removed. I'm supposing this keeps the cylinder bolt and plunger from slipping over one another and the bolt resetting. Fitting those relatively cheap parts seems to me the better approach than fiddling with hammer and trigger interaction.
 

dfletcher

Blackhawk
Joined
Sep 14, 2006
Messages
921
Captain America said:
I had a friend bring one by with a very similar problem after he disassembled it. He deformed the tiny spring in the trigger plunger, I had some because the good people at Ruger sent me five for free after I launched one through a hole in the fabric of the space/time continuum. It was an easy fix once I found it.

I also bought two of each of the hand and bolt springs. Don't see anything wrong with either, but that old saying "two is one, one is none" also applies to little gun parts that go flying, I've learned. ;)
 
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