G17: Changed trigger spring and safety plunger spring

[brianr34]

I have a G17 RTF2 that I use for IDPA and the range.

I have done the following mods:

Glock minus connector, 6 lb trigger spring and reduced safety plunger spring.

I really like the feel of the trigger. Changing the trigger and safety plunger spring has made the trigger smoother and reduced the initial take-up force.

To avoid any potential failures, I did not change the firing pin spring or change the weight of the recoil spring.

Is there any potential functional concerns that changing the trigger or safety plunger spring could cause? If so, what would the failure be?

Also, I ordered a 13 and 15lb IMSI spring. I was considering using the stock Glock guide rod with these springs. Is it OK to remove the cap and the end of the guide rod and then put it back on? I guess my other option is to just go with an uncaptured method?

Any feedback would be appreciated?

[MarkCO]

Glock minus connector, 6 lb trigger spring and reduced safety plunger spring... any potential functional concerns that changing the trigger or safety plunger spring could cause?

Also, I ordered a 13 and 15lb IMSI spring. I was considering using the stock Glock guide rod with these springs. Is it OK to remove the cap and the end of the guide rod and then put it back on?

No, those mods won't alter reliabilty, nor will the change any wear cycles. ISMI springs won't work well on the stock rod. Different IDs and flat coil v. round coil wire. I'm not sure what the IDPA rule is, but I'd go for a Steel rod if it is legal.

[Greg Bell]

I beg to differ ISMI springs work well on the stock rod, Wolff does not.

[MarkCO]

I beg to differ ISMI springs work well on the stock rod, Wolff does not.

No begging necessary.

When I tired it on my G22, the stock rod got all cut up and was on the verge of breaking after about 10K rounds.

[vluc]

Interesting. I've taken stock rods apart and placed ISMI on several of them, ran with no problems.

[Greg Bell]

MarkCO

That is very odd I have been doing that very thing on two different Glocks for some time now. I know a lot of others do as well.

[MarkCO]

Interesting. I've taken stock rods apart and placed ISMI on several of them, ran with no problems.

I agree, maybe it was just that one gun combination. Maybe I need to try another one.

[brianr34]

If I install the IMSI spring on the stock guide rod, should I just use it as uncaptured or should I remove and reinstall the cap on the guide rod.

I think I may start with the 15lb first. A little concerned that the 13lb spring may not return to battery correctly.

With the 15lb spring, what difference would I expect to see? Should it have less felt recoil and get back onto target faster? I normally use Blazer brass and aluminum 115gr ammo.

[Greg Bell]

I recap mine. Just experiment a bit with your own shooting and loads to see what feels good to you.

[ck1]

If I install the IMSI spring on the stock guide rod, should I just use it as uncaptured or should I remove and reinstall the cap on the guide rod.

I think I may start with the 15lb first. A little concerned that the 13lb spring may not return to battery correctly.

With the 15lb spring, what difference would I expect to see? Should it have less felt recoil and get back onto target faster? I normally use Blazer brass and aluminum 115gr ammo.

I ran (and may still go back to at some point) the almost identical set-up for a very long time... the 15lb spring will give you the slightly better sight-tracking you're probably looking for and will remain 100% reliable, with a 13lb recoil-spring and a stock striker-spring you are dead-on, it can become a guessing game as to when the 13lb spring will become too soft and start to give you problems, 15 is the way IMO (and after a bunch of rounds will get real close to what a 13 feels like anyhow, I ran one out to 6000+rds before I changed it for a fresh one without a single issue).

I always recapped the stock guide rod with no issues.

[brianr34]

Thanks for the feedback.

It is probably best if I just go with the 15lb. It is tempting to go with the 13lb, but I do not want to have any problems. It was mentioned that the 13lb is good initially, then over time it may become too soft. I assume this varies, but does it take a few hundred rounds to do this, or are we talking about a few thousand rounds.

Is there a test that can be done to determine if the recoil spring is strong enough, to try and detect any issues before it happens. For example, if you hold the gun vertically and slowly release the slide, if it goes back to complete battery, is this good enough?

I have never installed an IMSI spring on a stock Glock guide rod before. To I keep the IMSI spring at the stock length or do I have to clip some coils off, for it to work properly?

Edited December 30, 2010 by brianr34

[vluc]

Stock length fits fine. Be sure you have eye protection! Just in case.

[Duane Thomas]

I'm not sure what the IDPA rule is, but I'd go for a Steel rod if it is legal.

It's legal in Enhanced Service PIstol (ESP) but not in Stock Service Pistol (SSP).

[Duane Thomas]

It is probably best if I just go with the 15lb. It is tempting to go with the 13lb, but I do not want to have any problems. It was mentioned that the 13lb is good initially, then over time it may become too soft. I assume this varies, but does it take a few hundred rounds to do this, or are we talking about a few thousand rounds.

I have over 60k combined through my Glock 17 and 34, the VAST majority of that fired on ISMI 13-pound recoil springs, and I've never had a functional problem. I've run a single spring for up to 10k likewise without a single problem.

Is there a test that can be done to determine if the recoil spring is strong enough, to try and detect any issues before it happens. For example, if you hold the gun vertically and slowly release the slide, if it goes back to complete battery, is this good enough?

The classic test is as you describe, except you pull the trigger first and hold the trigger to the rear while pointing the muzzle straight up and slowly hand cycling the slide.

[ck1]

Duane, IIRC you've mentioned a bunch of times that you run reduced-power striker-springs in your Glocks as you roll your own using easy-to-set-off Federal primers... with a stock strength striker-spring installed, a 13lb recoil spring can be iffy at best, dangerous at worst. Depending on the particular specimen a 13 can go too-soft in only a few hundred rounds in one gun, while work for years and go thousands in another one. Also, with a stock-strength striker-spring installed and testing a 13lb recoil spring, I've found using the classic "muzzle-to-the-sky-reset-into-battery" method can lie to a guy... often a clean gun will pass when one that's only slightly dirty and seen as little as a box or two of rounds will fail.

IMHO: reduced-power striker-spring + 13lb recoil spring = GOOD, stock-power striker-spring + 13lb recoil spring = NOT GOOD (sooner or later anyways).

[MarkCO]

with a stock strength striker-spring installed, a 13lb recoil spring can be iffy at best, dangerous at worst. Depending on the particular specimen a 13 can go too-soft in only a few hundred rounds in one gun, while work for years and go thousands in another one. Also, with a stock-strength striker-spring installed and testing a 13lb recoil spring, I've found using the classic "muzzle-to-the-sky-reset-into-battery" method can lie to a guy... often a clean gun will pass when one that's only slightly dirty and seen as little as a box or two of rounds will fail.

IMHO: reduced-power striker-spring + 13lb recoil spring = GOOD, stock-power striker-spring + 13lb recoil spring = NOT GOOD (sooner or later anyways).

^ Agree!

[Nik Habicht]

IMHO: reduced-power striker-spring + 13lb recoil spring = GOOD, stock-power striker-spring + 13lb recoil spring = NOT GOOD (sooner or later anyways).

I think you're on the right track -- but it's not that simple. Anytime you make a change from stock springs, you need to know what could happen, and what checks need to be performed in order to safely run the gun....

While most of the time that's true -- reduced power striker spring + 13 lb. recoil spring = Good -- I've seen enough weird examples of guns not working quite right, to encourage everyone to check everything, to check often, and to carry spare parts....

Springs are dirt cheap compared to even the lowest ER bill....

[brianr34]

It sounds like it would be best if I just stuck with the stock 17 lb spring or maybe go down to 15 lb spring if I want to make a change.

I am concerned that I will get light primer strikes if I go to a reduced power firing pin spring. I mainly use Blazer Brass and Aluminum 115gr.

[ck1]

It sounds like it would be best if I just stuck with the stock 17 lb spring or maybe go down to 15 lb spring if I want to make a change.

I am concerned that I will get light primer strikes if I go to a reduced power firing pin spring. I mainly use Blazer Brass and Aluminum 115gr.

Exactly. If you want to try a 15lb spring it'll be safe but if the stock 17 feels good then no need to bother (IMO I prefer the 15, even more so once it's broken-in and has got more than a few hundred rounds on it). You are correct that a reduced-power striker-spring will NOT be fun if you're going to be shooting Blazer, it'll be light-strike-city.

Sometime, if you do get a hold of some ammo loaded with Federal primers, try out the reduced-power striker-spring + 13lb recoil-spring combo 'cause it is indeed nice, but the pound or so difference in trigger weight you get running a stock-strength striker-spring won't hold you back much if at all.

[brianr34]

Well, I tried out the 13 lb IMSI spring today. I probably should not have tried it, because it felt really nice compared to the 17 lb stock. It had less recoil and I was able to do double taps quicker. I was not timing, but I know there was a difference.

Along with the 13 lb spring, I have a Glock 3.5 connector, 6lb trigger spring and reduced power safety plunger spring. I am using the stock firing pin spring.

I also have a 15 lb IMSI spring, but I did not try it today. It is a pain to try and put the spring on an uncaptured guide rod.

I did not slide test of holding the gun vertical with the trigger depressed and the 13 lb spring has no problem going into battery.

What failure would I be likely to have if I stuck with the 13lb spring? Of course I don't want to have a kaboom, so I wanted to understand any warning signs before that happens.

I may just go ahead and buy the Jager plastic captured guide rod and install the 15lb spring. However, since I have felt how nice the 13lb spring is, it is tempting to keep using it.

One last question. I see Wolf makes a 14lb spring. Will this spring work OK on a Glock guide rod and/or the Jager plastic captured guide rod?

[JBP55]

The Wollf and ISMI springs are not the same design and the ISMI springs fit the OEM Glock guide rod. All my Jager guide rods have ISMI springs as well. Get the correct springs for your guide rod.

[brianr34]

Which IMSI spring do you use? (13 or 15 lb)

[JBP55]

Which IMSI spring do you use? (13 or 15 lb)

I have both but use the 15# for most applications.

[ck1]

You've really got to keep on eye on things if you're going to try running the 13lb recoil spring with a stock-strength striker-spring, it'll work for a little while, but guys running that set-up with success for any real length of time is pretty darn rare... some of the things to watch out for that are signs the 13 is getting over-powered by the striker-spring are: problems with the gun failing to return to battery, the slide "wiggling", shifting, or just looking strange while dry-firing it, and/or getting light-strikes and off-center primer hits (sometimes called "primer smearing"). Ignore those signs and you could be in for it as a Glock can and will fire out-of-battery and that would be bad for just your gun at best, or your hand and or well-being too at worst. The 15 is a more reliable and safer bet for sure.

A 14lb Wolff spring works fine on an un-captured stock Glock guide rod ,but Wolff springs in my experience come in softer for a given weight than the ISMI's, and I wouldn't recommend a Wolff 14lb recoil spring with a stock-strength striker-spring either as the one's I've tried have all been actually a bit lighter than an ISMI 13.

Not sure about the Jager rod as I do not own one, but they're advertised as working with stock springs so they should work with ISMI's I'd bet.

[JBP55]

You've really got to keep on eye on things if you're going to try running the 13lb recoil spring with a stock-strength striker-spring, it'll work for a little while, but guys running that set-up with success for any real length of time is pretty darn rare... some of the things to watch out for that are signs the 13 is getting over-powered by the striker-spring are: problems with the gun failing to return to battery, the slide "wiggling", shifting, or just looking strange while dry-firing it, and/or getting light-strikes and off-center primer hits (sometimes called "primer smearing"). Ignore those signs and you could be in for it as a Glock can and will fire out-of-battery and that would be bad for just your gun at best, or your hand and or well-being too at worst. The 15 is a more reliable and safer bet for sure.

A 14lb Wolff spring works fine on an un-captured stock Glock guide rod ,but Wolff springs in my experience come in softer for a given weight than the ISMI's, and I wouldn't recommend a Wolff 14lb recoil spring with a stock-strength striker-spring either as the one's I've tried have all been actually a bit lighter than an ISMI 13.

Not sure about the Jager rod as I do not own one, but they're advertised as working with stock springs so they should work with ISMI's I'd bet.

The ISMI springs work on a Jager guide rod and I agree with you on the spring weights and Wollf vs ISMI.