Author Topic: 75 Sear spring  (Read 999 times)

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Offline redlightrich

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75 Sear spring
« on: January 07, 2018, 10:24:25 AM »
Hello all. I realize this may be a touchy subject for some, however, it appears that the CZ 75B series pistol's trigger weight is influenced by several items.
Trigger return spring
Sear Spring
FP block assy ( and super light spring)
Mainspring
All this, along with the smoothness or lack thereof the lockwork.

There are ways to safely alter most of these items, however, I have not seen a reduced power sear spring for the 75B model.

I have not yet measured the sear spring's influence on the equation, but I will at some point soon. I actually bought a brand new one, so I can measure the base line against a well used one.

In the Ruger world, on Mk series pistols, there are reduced power sear springs available.  I do not use one in that application.

My question is, has anyone found a reduced power sear spring for the 75B? Has anyone experimented here sucessfully? Without hammer follow? Is it simply that the liability of offering said product is not worth the few ounces that may be gained?

The RP trigger return spring is a successful product, and it's weight reduction isn't tremendous, although it is noticeable.


I have searched this subject, and find nothing on it.

Any input would be welcome

Thank you

Rich

Offline Tok36

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Re: 75 Sear spring
« Reply #1 on: January 09, 2018, 08:39:00 PM »
I have not seen a reduced power sear spring available for CZ 75 variant pistols. I would assume that lack of need plays into their absence. Aside from the safety concerns that you mentioned, reducing the sear spring weight can also effect the feel of the SA break negatively.

While i prefer an SA around 3.5LB i have seen many other CZ owners get their SA pull down very low without a RP sear spring. What is your goal weight or were you just curious if the part existed?

Sear cage position and stability in the pistol frame can also play into the SA pull weight a bit.
Will work for CZ pics! (including but not limited to all CZ clones)

Offline fastlane604

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Re: 75 Sear spring
« Reply #2 on: January 09, 2018, 10:22:06 PM »
I have not seen a reduced power sear spring. I have changed my sear spring to a four coil Tanfoglio spring, the CZ spring is three coil. I wanted a stronger pull. The Tanfoglio spring was significantly stiffer and added 4 ounces to the trigger pull.  If a spring is installed that is as much lighter than the stock CZ spring as the Tanfoglio is stiffer, I think functionality may suffer.

I wanted a stronger pull, because my SA trigger pull was too light, for me. It was around 2.75 lbs. That can be easily attained with a good polish job, an RP trigger return spring, 13 lb (or lighter) hammer spring and a CGW race hammer.

If you want a lighter trigger pull than what those mods will give you, and you are willing to chance the results of a lighter sear spring, try bending the long arm of the spring to take out some of the tension.
« Last Edit: January 09, 2018, 10:24:18 PM by fastlane604 »

Offline copemech

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Re: 75 Sear spring
« Reply #3 on: January 09, 2018, 11:54:23 PM »
Not reccomended O0

Offline copemech

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Re: 75 Sear spring
« Reply #4 on: January 09, 2018, 11:56:12 PM »
Who has light sear springs for a Ruger MkII ?

Offline 1SOW

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Re: 75 Sear spring
« Reply #5 on: January 10, 2018, 12:52:31 AM »
With a little TLC  and parts fom CZC or CGW the trigger pull can be reduced nicely in "DA".  When the DA gets down to 5# the SA can get awfully light.....like 2.5 pounds or even lower with a comp hammer.  This leads some to INCREASE the sear spring weight to bring the SA pull up a skosh without increasing the DA pull.  Not much need for a lighter sear spring has shown up. 


 

Offline doc171

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Re: 75 Sear spring
« Reply #6 on: January 10, 2018, 12:17:04 PM »
I have not seen a reduced power sear spring. I have changed my sear spring to a four coil Tanfoglio spring, the CZ spring is three coil. I wanted a stronger pull. The Tanfoglio spring was significantly stiffer and added 4 ounces to the trigger pull.  If a spring is installed that is as much lighter than the stock CZ spring as the Tanfoglio is stiffer, I think functionality may suffer.

I wanted a stronger pull, because my SA trigger pull was too light, for me. It was around 2.75 lbs. That can be easily attained with a good polish job, an RP trigger return spring, 13 lb (or lighter) hammer spring and a CGW race hammer.

If you want a lighter trigger pull than what those mods will give you, and you are willing to chance the results of a lighter sear spring, try bending the long arm of the spring to take out some of the tension.
Yes but, I believe I am saying this correctly, the tension of a spring has two variables...One is the number of coils as stated above and THE WIRE DIAMETER. So, could the four coil have a thinner diameter wire used verses the CZ which has three coils ?
« Last Edit: January 10, 2018, 04:48:22 PM by doc171, Reason: Made error in reading quoted post »

Offline fastlane604

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Re: 75 Sear spring
« Reply #7 on: January 10, 2018, 04:06:10 PM »
I have not seen a reduced power sear spring. I have changed my sear spring to a four coil Tanfoglio spring, the CZ spring is three coil. I wanted a stronger pull. The Tanfoglio spring was significantly stiffer and added 4 ounces to the trigger pull.  If a spring is installed that is as much lighter than the stock CZ spring as the Tanfoglio is stiffer, I think functionality may suffer.

I wanted a stronger pull, because my SA trigger pull was too light, for me. It was around 2.75 lbs. That can be easily attained with a good polish job, an RP trigger return spring, 13 lb (or lighter) hammer spring and a CGW race hammer.

If you want a lighter trigger pull than what those mods will give you, and you are willing to chance the results of a lighter sear spring, try bending the long arm of the spring to take out some of the tension.
Yes but, I believe I am saying this correctly, the tension of a spring has two variables...One is the number of coils as stated above and THE WIRE DIAMETER. So, could the four coil have a thinner diameter wire used verses the CZ which has four coils ?

I am on the road, so I can't compare the wire diameter of the Tanfoglio vs the CZ spring, but I can tell you without a doubt that  the Tanfoglio spring is stiffer.

Offline redlightrich

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Re: 75 Sear spring
« Reply #8 on: January 11, 2018, 09:28:51 AM »
Thank you for the answers and thoughts, I don't think I will change it out, I was just curious as to what it would do. My fear is it may be prone to doubling or some other bad behavior, like incomplete sear reset.
Currently, my CZ75 is at 2.5# in SA. I don't really need it any lower, but at 2#, it would be the same as my 41 and MkIII. I don't concern myself with DA, as that is not what I use for target.

For those wondering how I achieved 2.5#, I used a new sear and a CZC Modded Shadow hammer, polished trigger bar, polished MS/Hammer strut, CGW RP trigger return spring ( this actually makes a big difference for 7 dollars and reset is fine) I have also installed a 17# mainspring. Trigger feel is crisp. No more camming of the hammer, and creep is tiny. I only have 425 rounds or so with this set up, so the small amount of creep may disappear as the sear and hammer seat. I do believe it will.

I intend to measure the sear spring weight the next time I take this pistol apart. I am not sure what I will do with that info, but it may be helpful in the future to someone.

In my set up, I paid zero attention to the trigger bar spring. Which ever way it was set at the factory is how it is. My guess is if set to perfection, some friction could be lost, so as a result, an ounce or 2 may be removed from trigger pull. It appears that the trigger bar, riding against the underside of the slide, controls out of battery issues, so I approach that with caution as well. If I am correct in how I believe this works, then the trigger bar/slide are the actual disconnector as opposed to what we call the disco ( which is not there in a SA only gun) so it makes me think I am correct.

What is the lowest recorded SA pull on a 75B  while maintianing safety, and a normal, predictable trigger feel? Does anyone have a 1.5 or 2# trigger that behaves properly and feels good?

BTW to whoever asked about the MkIII sear spring, when I purchased a VQ sear, it comes with a new spring that appears to be smaller diameter wire. I didn't actually measure the weight, but being the diameter was smaller, but the windings were the same number, I assumed it was a RP spring. I choose to use the factory sear spring on the Mk, with no bad effect at all.

Again, thanks for thoughts and insights. Anyone have a low # trigger on their 75B and care to weigh in?

Rich

Offline ThompsonCustom

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Re: 75 Sear spring
« Reply #9 on: January 11, 2018, 05:06:35 PM »
It's been awhile since I've done one under 2lbs but ya it's more than doable I think there was a guy over on the Brian enos forums that got under 1lb.

Couple of questions for ya

Have you removed the firing pin block and lifter yet? if not that would be the first thing I would do. Some other improvements you can do are: Stabilize the sear cage, Replace the sear pin with a polished tool steal pin, Polish the contact points on the bottom side of the sear cage, I'm sure there's more but that's all I can think of at the moment.

To answer your question about the spring under the trigger bar. With you firing pin block and lifter removed you can tweak the trigger bar lifter spring down wards and shave a little off.

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Offline coolbox

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Re: 75 Sear spring
« Reply #10 on: January 11, 2018, 11:38:42 PM »
My Sp01 Shadow is at 2 lbs with regular trigger and sear springs, a lot of shooting and love (polish), comoetition hammer and reduced power hammer spring (13 lbs). I shifted to oem factory hammer spring to get it up to 2.2 lbs.
With ths 13 lbs hammer spring, i used extended firing pin.
Life is too short to waste on a bad trigger pull

Offline M1A4ME

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Re: 75 Sear spring
« Reply #11 on: January 12, 2018, 07:48:31 AM »
I don't think I've read about anyone buying/selling/using l lighter powered sear spring in a CZ 75.  Why?

My Tactical Sport .40 S&W has around 1&3/4 lb. SA trigger pull (bought it that way).

My SP01 Compact 9MM has around 2&1/4 lb. SA trigger pull (put the parts in myself.)  I installed the trigger, a reduced power firing pin block spring, a reduced power trigger return spring, a reduced power firing pin spring a 15 lb. hammer spring and the CGW race hammer and adjustable sear and did just a little bit of stoning/polishing on the trigger bar sides.

Seems like I have heard of people installing a stronger sear spring in an attempt to increase the trigger pull weight when previous mods. result in a trigger pull weight they feel is too light.
Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.

Offline redlightrich

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Re: 75 Sear spring
« Reply #12 on: January 12, 2018, 09:26:43 AM »
Again, I sincerely appreciate the thoughts and experiences. They help me and others learn.
Thompson, No I didn't yet remove the FPB lever or spring, but I have a Pre B sear and a spacer, so I can do that either of those ways, and probably will. That should lower pull weight and shorten reset. I have a Shadow (SP-01) top end on the way, so that will be fine.
I have not polished the underside of the sear cage yet, but I will. The sear pin, really becomes a mess after 1000 rounds or so, so a tool steel pin is a great idea. By a mess, I mean you can see the factory coating wearing off, and slight wear marks in the soft steel.
My gun is a SS 75B with ambi safety, so sear cage is held in 3 places ( Right and left safety lug and rear notches). How does one further stabilize this? Shims?

Cool, thank you for the MS info, my issue is that I use a lot of rimfire ammo ( I convert often to Kadet). For me to get 100% ignition ( even if the chamber gets dirty) the 17# MS is about as low as you can go without further mods. I have bought a few new firing pins that I may modify to increase the effective length, then I could drop the MS. Without the FP mods, even dropping to 16# ( yes I tried) results in FTF from light strikes. My hesitation is that once I lengthen the FP effective length, I may lose the ability to dry fire, as on rimfire, the pin can strike the chamber edge if it protrudes at full extension. This can happen even if you are aware and being careful, such as shooting a mag ( and  not carefully counting shots), and the last round is a touch weak, the shell ejects and hammer cocks, but the slide isn't locked back, you pull the trigger and click. Damage to chamber. Yes, it can be fixed, but I hate that thought.

M1A, Why? I guess I am just wondering if a few ounces could be shaved off without sacrificing safety and reliability. I have seen the increased power spring you spoke of, but don't remember if it was sear, FPB, or actually the trigger return? I will look. I think I saw it on CGW site.

If I could get this gun to 2# SA, I will be very happy. That would be consistent with my other target pistols. The funny thing is, I was reading my notes from last year ( I keep notes on all my work so I can review and trace my steps and gauge results) and at that time, my goal was a 2.5# trigger( factory was 5# SA, which seems the case on all my CZ pistols). Now that I am there, I want a 2#. Goofy human nature I guess?

If I don't have to ruin too many parts, I may be interested in going even lower than 2#, just for the sake of knowledge, but for me, I would want 2#. I am already close, at 2.5 and I still need to do a few more mods, so I am fairly confident I could make it.

Thank you for your help!! I do appreciate it!!

Rich

Offline M1A4ME

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Re: 75 Sear spring
« Reply #13 on: January 12, 2018, 10:47:56 AM »
The hammer spring is really pushing that hammer down on the sear.  I don't think it'll "bump" loose.  If you leave the firing pin block in that's an extra layer of safety.

I wonder is anyone's done a study (not just trigger pull force required to release the hammer) but a combination of friction (surface conditions on the parts that slide/rotate against each other) and spring forces (hammer, sear, firing pin block and trigger return spring) just to see what effect a lighter or stronger trigger return spring or sear spring would have.

Most folks here (if I remember correctly) feel a heavier or lighter hammer spring really doesn't affect the SA trigger pull (DA yes, SA no).

For my part, I don't notice the force required to move the trigger rearward from sear reset to just before the sear releases the hammer again.  I take that up automatically, after firing, just like I do on a rifle.  My finger is on the trigger, it moves the trigger to the rear until the trigger stops and then when I'm ready (with a good trigger) a little more rearward movement releases the hammer.

What I do notice is any little bumps/drags between sear reset and that point just before the sear releases the hammer and any unnecessary trigger rear movement (more dragging, bumping, etc.) before it releases the hammer.

If you look at the pictures of hammers on the CZ USA, CZ Custom, CGW websites you see varying degrees of "room" between the bottom of the full cock notch (where the sear stops) and the top of it (where the sear releases the hammer).  Some are really "short" vs. others.  So far, "short" has resulted, for me, in a very crisp trigger pull.  Now, crisp may not really be light, but if it's crisp then it feels lighter to me than it really is.  My CZ 85 Compact (a clone I put together) has a 3 lb. SA trigger pull.  I actually measured it 3 or 4 times that first time because is was so crisp I just knew it was lighter than 3 lbs. and therefore I kept giving the trigger pull gauge the opportunity to show the correct reading because I must have been doing something wrong, or the gauge had failed.  But it was just a very nice, very crisp trigger pull in SA.

Working on the trigger pull can be rewarding.  A nice trigger is, nice.  Makes a gun more enjoyable to shoot, for me anyway.
Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.

Offline ThompsonCustom

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Re: 75 Sear spring
« Reply #14 on: January 12, 2018, 04:37:20 PM »
Quote
The sear pin, really becomes a mess after 1000 rounds or so, so a tool steel pin is a great idea. By a mess, I mean you can see the factory coating wearing off, and slight wear marks in the soft steel.
My gun is a SS 75B with ambi safety, so sear cage is held in 3 places ( Right and left safety lug and rear notches). How does one further stabilize this? Shims?

There's a handful of ways you can stabilize the cage but the easiest is to get a longer #19 pin (on the cz 75 parts diagram) and fit it so the sear cage just fits into place. Cajun Gun Works should be able to hook you up or you can order the sear pin and #19 pin through Mcmastercar
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