redlightrich
New member
Hello all, I am hoping that someone with experience can help me with these questions.
I have a Ruger GP100 in .22lr, that I have been "tuning". In an effort to lower trigger pull effort, I installed a Wolff spring kit. For purpose of this question, I will focus only on the hammer spring.
Mistake number one is I DO NOT know what the factory hammer spring is rated at in pounds.
In my Wolff kit, there were 3 hammer springs, the heaviest was 12#. This is the spring that I installed. Naturally, the trigger lightened, but I have some FTF with this arrangement. It is however very close to ideal. If I thoroughly clean the chambers, I can get about 2 ftf's in the first 100 rounds. After that, when the chamber is nice and gunked up, I get about 1 ftf per cylinder full on most ( not all) reloads. This is a 10 round wheel.
In studying the FTFs ( I have not yet determined if it is the same chamber that FTFs, but I have a suspicion) the non firing pin marks are very similar to ones that actually fired. Some of the FTFs are ammo related as I take the non firing rounds, and spin them to give a fresh area and still no bang. I am using various types of cheap bulk ammo. In my thoughts, the ability to use cheap ammo is one benefit of a revolver. I have used some good ammo as well, and although it gets a little better, it is clear to me I need a stronger whack!!
My guess is I need to raise the hammer spring pressure just slightly to eliminate the FTFs. I would think a 13# spring would all but eliminate any issue. It is that close
Can I shim the spring? I know when I was in my previous life as an automotive machinist, I used to routinely install spring shims. This was done in an effort to restore valve spring pressure ( on cheap rebuilds) or to fine tune pressure when installing all new parts. I had a spring pressure gauge/stand, which took any guess work out of the equation. I set the compressed length and read the gauge when closed on a spring. I added the shim, and took a measurement, and made sure there was no chance of binding. Yes I am over simplifying what occurred, but that is the basic idea.
Shims were either .030 or .060 for used springs, and of various sizes for fine tuning new springs. I personally never used any shim below .015 due to my fear that it may "rip" or tear when in service.
My automotive machine days were a long time ago. I no longer remember the actual numbers and percentages that the shims added to the pressure reading. I do know the springs were very thick wire and about 1.750 free length with pressure that exceeded 150 psi.
Does anyone have any input on this? How much pressure would be added if I installed a shim of say .020 or .030? I realize I can simply buy a heavier spring, but that defeats my "tuning".
I like the current trigger, and would like to up the pressure just enough to end the FTFs. This will never be a defense gun, so I am not afraid of the potential to very rarely FTF. It is a range gun, no competition, so very close, is good enough..
I have already ordered actual hammer shims ( this is to remove any potential drag that can occur if the hammer rides against the frame). These shims have nothing to do with the hammer spring pressure, although any reduced drag can help here.
Any engineers out there can weigh in? Has anyone ever used shims to raise the pressure? Of course I will be sure to check that the shim does not make the coils bind at full compression.
Thank you for reading my long winded request for help!!!
Rich
I have a Ruger GP100 in .22lr, that I have been "tuning". In an effort to lower trigger pull effort, I installed a Wolff spring kit. For purpose of this question, I will focus only on the hammer spring.
Mistake number one is I DO NOT know what the factory hammer spring is rated at in pounds.
In my Wolff kit, there were 3 hammer springs, the heaviest was 12#. This is the spring that I installed. Naturally, the trigger lightened, but I have some FTF with this arrangement. It is however very close to ideal. If I thoroughly clean the chambers, I can get about 2 ftf's in the first 100 rounds. After that, when the chamber is nice and gunked up, I get about 1 ftf per cylinder full on most ( not all) reloads. This is a 10 round wheel.
In studying the FTFs ( I have not yet determined if it is the same chamber that FTFs, but I have a suspicion) the non firing pin marks are very similar to ones that actually fired. Some of the FTFs are ammo related as I take the non firing rounds, and spin them to give a fresh area and still no bang. I am using various types of cheap bulk ammo. In my thoughts, the ability to use cheap ammo is one benefit of a revolver. I have used some good ammo as well, and although it gets a little better, it is clear to me I need a stronger whack!!
My guess is I need to raise the hammer spring pressure just slightly to eliminate the FTFs. I would think a 13# spring would all but eliminate any issue. It is that close
Can I shim the spring? I know when I was in my previous life as an automotive machinist, I used to routinely install spring shims. This was done in an effort to restore valve spring pressure ( on cheap rebuilds) or to fine tune pressure when installing all new parts. I had a spring pressure gauge/stand, which took any guess work out of the equation. I set the compressed length and read the gauge when closed on a spring. I added the shim, and took a measurement, and made sure there was no chance of binding. Yes I am over simplifying what occurred, but that is the basic idea.
Shims were either .030 or .060 for used springs, and of various sizes for fine tuning new springs. I personally never used any shim below .015 due to my fear that it may "rip" or tear when in service.
My automotive machine days were a long time ago. I no longer remember the actual numbers and percentages that the shims added to the pressure reading. I do know the springs were very thick wire and about 1.750 free length with pressure that exceeded 150 psi.
Does anyone have any input on this? How much pressure would be added if I installed a shim of say .020 or .030? I realize I can simply buy a heavier spring, but that defeats my "tuning".
I like the current trigger, and would like to up the pressure just enough to end the FTFs. This will never be a defense gun, so I am not afraid of the potential to very rarely FTF. It is a range gun, no competition, so very close, is good enough..
I have already ordered actual hammer shims ( this is to remove any potential drag that can occur if the hammer rides against the frame). These shims have nothing to do with the hammer spring pressure, although any reduced drag can help here.
Any engineers out there can weigh in? Has anyone ever used shims to raise the pressure? Of course I will be sure to check that the shim does not make the coils bind at full compression.
Thank you for reading my long winded request for help!!!
Rich