hoptob
Member
WARNING. RUGER STRONGLY ADVISES AGAINST ANY MODIFICATIONS OF THE TRIGGER SEAR AND HAMMER NOTCH ANGLES. IF YOU CHOOSE TO DO SO, YOU ASSUME FULL RESPONSIBILITY FOR ALL CONSEQUENCES INCLUDING DAMAGE TO YOUR GUN WHICH WILL REQUIRE EXPENSIVE FACTORY REPAIRS. RUGER DOES NOT SELL TRIGGER, HAMMER OR HAMMER DOG; THESE PARTS MUST BE FITTED AT THE FACTORY. I AM NOT TRAINED AS A GUNSMITH AND ASSUME NO RESPONSIBILITY FOR ANY DAMAGE YOU MAY CAUSE BY THESE OR OTHER MODIFICATIONS. IN OTHER WORDS, YOU ARE ENTIRELY ON YOUR OWN!
Last Christmas I gave myself DAO 2 1/4” Ruger SP101. Nice little gun but action was not good out of the box.
I followed action job procedures kindly provided by Gary/Iowegan. I am really indebted to Gary. Fine gentlemen and skilled gunsmith, Gary took time to summarize his considerable expertise in an excellent Iowegan Book of Knowledge also known as IBOK. Gary’s book is a must have for all Ruger revolver owners who want to understand and improve upon these fine arms.
After cleanup and extensive polishing of many various parts, action of my SP101 became smooth and reasonably light. Yet, it did not quite match fine trigger pull of GP100 or S&W revolvers. At the very end of the pull too much pressure was needed to break the trigger. Granted, SP is not meant as a target revolver, but in my humble opinion there is nothing wrong with having fine trigger on a carry gun. Fine, not light. So, I set off to improve upon it.
Around same time I was reading “The Modern Gunsmith” classic by James V. Howe (1934). There I ran into old master's words “The factories strongly advise against touching the hammer notch; nevertheless, this is the secret of a very fine pull in these arms [revolvers]”. Well, here was the secret.
Started by carefully studying J. Howe’s excellent treatise and geometry of SP101 DA sear. It became clear that too much pressure at the end of the pull was caused by the shape of hammer notch. Unlike GP100 or any other revolver I own, SP101 has concave notch.
As trigger slides to the break point, steep angle of the notch causes considerable movement of the hammer against pressure of the mainspring. The steeper is the angle the more pressure shooter will feel. My plan was to cut off the hump at the end of the hammer notch - red line in the picture above. If done carefully, this cut should reduce trigger pressure but leave timing almost unchanged.
The rest was not very difficult. Armed with a loupe, good Norton stone and square steel blocks, I cut the hammer notch, trued up trigger sear, shortened hammer dog (by appr. 0.05”) and polished everything up. Here it what I got:
Trigger pull improved miraculously. Nicely smooth and firm with the stock springs, it became light just where I needed it – at the very end of the pull. Timing was perfect. In fact cylinder lockup point moved slightly away from the edge of the hammer notch leaving plenty delay before the break.
All done and dusted, this project was a sound success. New SP101 is a keeper.
I want to finish this post with a second word of warning for amateurs like myself who may be tempted to improve upon their SP101’s. Here is another quote from J. Howe “When a user of a target revolver attempts to doctor up his pull, it usually results in returning the weapon to the factory; or if it happens in my bailiwick, the sad report of a new trigger and hammer reaches me. For the beginner this is a job requiring considerable forethought, and too much care or patience can not be exercised.” This can be done but there is a reason why shaping sears is considered one of the most delicate jobs in gunsmithing trade.
Mike
Last Christmas I gave myself DAO 2 1/4” Ruger SP101. Nice little gun but action was not good out of the box.
I followed action job procedures kindly provided by Gary/Iowegan. I am really indebted to Gary. Fine gentlemen and skilled gunsmith, Gary took time to summarize his considerable expertise in an excellent Iowegan Book of Knowledge also known as IBOK. Gary’s book is a must have for all Ruger revolver owners who want to understand and improve upon these fine arms.
After cleanup and extensive polishing of many various parts, action of my SP101 became smooth and reasonably light. Yet, it did not quite match fine trigger pull of GP100 or S&W revolvers. At the very end of the pull too much pressure was needed to break the trigger. Granted, SP is not meant as a target revolver, but in my humble opinion there is nothing wrong with having fine trigger on a carry gun. Fine, not light. So, I set off to improve upon it.
Around same time I was reading “The Modern Gunsmith” classic by James V. Howe (1934). There I ran into old master's words “The factories strongly advise against touching the hammer notch; nevertheless, this is the secret of a very fine pull in these arms [revolvers]”. Well, here was the secret.
Started by carefully studying J. Howe’s excellent treatise and geometry of SP101 DA sear. It became clear that too much pressure at the end of the pull was caused by the shape of hammer notch. Unlike GP100 or any other revolver I own, SP101 has concave notch.
As trigger slides to the break point, steep angle of the notch causes considerable movement of the hammer against pressure of the mainspring. The steeper is the angle the more pressure shooter will feel. My plan was to cut off the hump at the end of the hammer notch - red line in the picture above. If done carefully, this cut should reduce trigger pressure but leave timing almost unchanged.
The rest was not very difficult. Armed with a loupe, good Norton stone and square steel blocks, I cut the hammer notch, trued up trigger sear, shortened hammer dog (by appr. 0.05”) and polished everything up. Here it what I got:
Trigger pull improved miraculously. Nicely smooth and firm with the stock springs, it became light just where I needed it – at the very end of the pull. Timing was perfect. In fact cylinder lockup point moved slightly away from the edge of the hammer notch leaving plenty delay before the break.
All done and dusted, this project was a sound success. New SP101 is a keeper.
I want to finish this post with a second word of warning for amateurs like myself who may be tempted to improve upon their SP101’s. Here is another quote from J. Howe “When a user of a target revolver attempts to doctor up his pull, it usually results in returning the weapon to the factory; or if it happens in my bailiwick, the sad report of a new trigger and hammer reaches me. For the beginner this is a job requiring considerable forethought, and too much care or patience can not be exercised.” This can be done but there is a reason why shaping sears is considered one of the most delicate jobs in gunsmithing trade.
Mike
