Washer for captured flock guide rod

[mlk3454]

I got an ISMI captured guide rod to mate with a 22lb recoil spring for my G20. The package came with a plastic/rubber type of washer and when installed with with the screw the spring bends it out almost beyond the screw. The screw by itself seems to hold the spring just fine....is this washer needed, it doesn't seem to be very effective as it is pliable with the spring in place.

The instructions do not note anything about a washer but they really are not very in depth instructions other than to put the spring on - add purple or blue loctite and screw in the screw at the end of the rod...any help is appreciated!

[Yondering]

The washer is for use with the long slides; it is needed to prevent the spring binding against the barrel. With the stock Glock slide you shouldn't need it.

[DM1906]

The washer isn't necessary for function in a standard length Glock slide, as Yondering said.  However, as I've found, if you don't use the washer, the actual spring weight will be a bit short of advertised, and just over if it's installed.  About 4 oz. on the 20, and about 7 oz. on the 24.  It isn't much, but does make some difference at 75% spring compression, which is where all my ISMI springs indicated the advertised weight (as they should).

[Yondering]

The washer isn't necessary for function in a standard length Glock slide, as Yondering said.  However, as I've found, if you don't use the washer, the actual spring weight will be a bit short of advertised, and just over if it's installed.  About 4 oz. on the 20, and about 7 oz. on the 24.  It isn't much, but does make some difference at 75% spring compression, which is where all my ISMI springs indicated the advertised weight (as they should).

How are you measuring spring weight? You've mentioned before that your ISMI springs meet the advertised weight, but mine don't come anywhere close to it. Also, the advertised weight should be when the slide is all the way to the rear, which is a good bit more than 75% compression in a G20; it's pretty close to full compression.

My spring test results below. Note the 17# vs 20 and 24# ISMI springs. These numbers do make sense when looking at the springs, because the 17# and 20# springs I have are exactly the same thickness and # of coils, but the 20# is just stretched out a little farther. The 24# are also the same thickness, but with a couple extra coils. (I made these measurements about a year ago, but finally got around to putting the chart on photobucket yesterday.)

[EdMc]

The 20 lb ISM seems most linear......something I'd think would be desirable in a mechanical application.

[Yondering]

They are all pretty linear (except the dual spring setup). The bumps and wiggles in the plot lines are from friction between the spring coils and the guide rod, and from the springs trying to "kink", as they don't compress naturally in a straight line but try to escape to the side.

Also, you can see the 17# and 20# ISMI springs are the same rate; this is because they are all the same spring, just stretched or wound longer for the heavier weights. The 24 lb springs do have 2 extra coils, which makes the spring rate slightly lower, but is otherwise the same as the 17# and 20#.

[mlk3454]

Just an FYI for anyone that may end up with the same question as me...

I called the tech line for ISMI and spoke with a very nice gentleman regarding that washer. He told me that he personally doesn't use the washer in his guns and that they are there more for the use with non ISMI springs that have an inner diameter bigger than the ISMI bretheren. He did mention that Wolf springs most likely will need the washer. Furthermore, he noted when installing the spring there will always be a side with a tighter inner diameter and that side should be installed on the screw end.

[RMM]

Yondering,

Nice graph! Is there any way that you could test some of the non-captured Wolff springs?  I am mainly interested in whether or not they provide a significant increase in pre-load (force exerted on slide when closed and in battery). 

There have been some anecdotal reports saying that they do indeed do this, but nothing quantitative that I have been able to find so far.

It is interesting to see the dual-spring at work!

[Driftwood]

Nice graph!  I have a question though...What is the dual spring?

[sqlbullet]

Dual spring set-up's have two springs in the recoil rod, which usually is of a telescoping nature. 

http://firearms.fortreg.com/?p=2723

[The_Shadow]

This is the Wolff 21 lb RSA for my G-29 

[Yondering]

Yondering,

Nice graph! Is there any way that you could test some of the non-captured Wolff springs?  I am mainly interested in whether or not they provide a significant increase in pre-load (force exerted on slide when closed and in battery). 

There have been some anecdotal reports saying that they do indeed do this, but nothing quantitative that I have been able to find so far.

It is interesting to see the dual-spring at work!

I'd be happy to test some of the non-captured Wolff springs, but don't have any. If someone wants to loan me some for testing, I can do that. I know the guide rod is different too, my LW rods would probably work for the spring tester but may give slightly different results.

Driftwood, I don't know what brand this dual spring is, but it's similar to the Sprinco dual spring setups. Function is different than the Glock dual spring setups for the compact pistols (like what Shadow posted), where both springs are compressed through the full range of travel. With this Sprinco-type setup, the main spring is compressed for a ways before the second internal spring is compressed. The second spring acts like a buffer, as you can see in the plot.

[RMM]

I would send you some to play with if I had any.  I am thinking about buying a set however, but was hoping to see how they actually compare. 

Anyone else have any extras laying around?   

[The_Shadow]

This is the Wolff 21 lb RSA for my G-29 

When this RSA is inside the pistol the small inner rod is barely sticking through the front of the slide, the springs are compressed to where it fits like the normal RSA, but you can feel the amount of preload is greater that the factory setup.
That is one reason I like this non-captive set-up, the other resaon is spring change out is quick and easy.

If an when I get the G-20 I'll be looking to get a similar set-up if it is available...

[RMM]

Yondering,

Are you still able and willing to test a Wolff spring setup?  I just ordered a Wolff guidrod and 22 pound uncaptured spring.  I would be willing to send it to you if you could test it and add it to the existing graph. 

I still wonder if we are messing with things that we shouldn't be in the G20 by switching from the stock polymer guide rod.  You can tell that it flexes quite a bit under recoil, whereas the metal rods are probably flexing much less.  I wonder if somehow this introduces additional binding somewhere in the system, especially with the polymer frame flexing under recoil.

I think that the dual-spring setups probably aren't as sensitive to this change, as the polymer setups are already much more rigid IMO than the single spring style.

I do have a brass stacker captured stainless guide rod with a 22 lb ISMI spring that I have used back-to-back with the stock spring.  The spring does not feel that much stiffer when racking the slide, but the "friction" of it does feel/sound slightly different.  The problem is that I don't have any objective way to measure the difference and I know that my perceptions are often incorrect.

Although I am not certain of this, I do think that in some instances the slide is unlocking early enough to bulge the brass beyond the normal chamber support.  I am not sure how much additional preload would be needed to change the timing enough to make any difference, or if it is even possible to do so without destroying the reliability of the gun.  At some point, I think that we just might be asking too much from the platform and cartridge.