Experience with ISMI springs.

[GordonB]

*** The Short Version ***

For those of you who have an ISMI spring, could you guys check out the flats of the spring (i.e. the flat portions of the spring between the coils).  My 13lb ISMI spring is buckled almost throughout the length of the spring.  The difference is obvious between the stock spring and my ISMI spring.  The stock Glock spring is very flat.  Do your ISMI spring(s) have these flaws?  If you have an unused one, does the new one have these flaw?  When did you buy the spring?

I want to find out if the flaw occured with the use of the Alchemy SS rod or if it lies with ISMI (i.e. has bad QC or had a bad batch of Glock springs).

I bougth the spring about 3 months ago from Brownell's.

*** The Long Version ***

I just received the CGR extended tungsten rod for my G34.  I assembled it with a used a 13# ISMI spring.  The ISMI was previously used for ~400-500 rounds with an Alchemy Arms SS rod.

After reading Doc's threads on his problems, I checked out the slide travel with the the GCR rod and the ISMI.  The travel of the slide barely cleared the slide release.  Popping in a stock recoil spring assembly and a factory spring with the GCR rod produced an extra ~3/16" of travel.  So the problem was with the ISMI spring.

There was a post that Glock changed how the guiderod tunnel was cut in the slides.  But from visual inspection, the outside diameter of the ISMI was not even a hair's width larger than the stock spring.  So it had to be the solid length of the spring that was causing the slide to not completely open.

So I measured the closed length of a stock spring at 15/16" and the ISMI spring at 1 and 4/16-5/16".  These measurements include an additonal ~3/16" due to the ruler's lead and the head of the guiderod --- so your measurement will vary.  The closed appearance of the stock spring was solid while the closed ISMI spring had gaps.

So easy enough, the solution I came up with was to cut the ISMI spring so that its solid length would match or come close to the stock spring's solid length.  

As I was cutting off the ISMI spring, I noticed that the spring was flawed.  The spring was buckled which caused the gaps when the spring was measured for its closed length and which in turn caused it to have a larger lenth than the stock spring.

.... insert the short verion.  

[Guest Dick W Holliday]

i got one with a heavy package from Glockracer (a 13# i think) and it just bearly cleared the magwell....i noticed the buckles you mentioned.......in order to get mine to work i had to cut a bunch off of it (sorry i can't tell you how much-i just started grinding till it went back as far as a comparable factory spring)....The ISMI guy was telling me that he is going to run some more soon that will be of smaller outside diameter and the center will be smaller too and may not fit some aftermarket guiderods.....he also said that when his current springs compress, the OD gets bigger and may be binding up in the channel.....DICK

[TRG65]

I've compared 3 ISMI 13's to the 5 factory springs I have on hand.  the glock springs have 37 coil and the ISMI springs have 39.  After I clipped 2 coils, I still could not pull the slide back as far as with the factory spring.  My final set up was clipping about 4.5 coils and a buffertech shock buff.  I like the feel of the shock buff, better than straight spring.  I still can't pull the slide back as far as I could with the factory assembly, I would need to cut probably another 3 coils.  

[GordonB]

Do your ISMI springs exhibit buckling?

[Flexmoney]

GordonB,

I think the buckling comes after we get a hold of them.

[TRG65]

Gordon,

Yes I have 2 that are buckled and one that isn't.  I agree with Flex.  I think it is our using them that causes the buckling.  The one that isn't buckled I haven't used.  I have pretty much said to ---- with ISMI spring and am just cutting stock Glock springs down until they feel right.

[Fireglock]

I just checked the 13 and 15 ISMI I have and neither have the buckling you mention. The 13 is over a year old, the 15 I put in my 17L in November. I got it from one of my teammates so I'm not sure how long it was in his bag. I can see the difference in slide travel between the 17L with an ISMI and my 17 with stock but both operate correctly when shooting. We use excessively light loads but I've had no functioning trouble with either gun.

[TRG65]

I just got a brand new 13# direct from ISMI.  It was buckled.  So I guess the theory about use causes the buckling might not be correct.

[GordonB]

Well the above would lead me to conclude that ISMI has crappy or a bad batch of Glock springs.

My used G17 is still on its original (when I got it) guiderod and spring and it has maybe 5000+ rounds that I have put through it and whatever the previous owner put through it.  The spring is flat and there is no buckling.

If the ISMI did somehow buckle when used then it is junk (I only used mine for ~500 rounds before I noticed the buckling).  And if the ISMI comes like that from the factory (as in HTR's case), then again it is junk.

I hope they get they their act together and either pull the bad springs from the market or improve their spring.  I'm going to stick with the factory springs until they do...