# variance between brands

[Wesquire]

I've read somewhere that Wolff tends to be the most accurate in terms of poundage, and that ISMI springs tend to actually be lighter than they say. I've heard that a 13# ISMI spring is more comparable to an 11# Wolff. Can anyone confirm this? I know that 13# ISMI is the standard for glock 34s, I just ordered a Wolff 12# because ISMI springs won't fit on my guide rod. Think this will be too light or about right?

[Whitefish]

My experience is the opposite. I use a 14 lb Wolff recoil spring in lieu of the 13 lb ISMI in most of my 9mm Glocks. I do have a 13 lb ISMI in one Glock 34 and that spring rate feels and behaves about the same as the 14 lb Wolff in the other 9mm Glocks. A 12 lb Wolff may work just fine depending on you load and gun, but I think it is too light given my experience.

[Wesquire]

Are either of the springs flat-wire? Also, my loads are super light.

[Whitefish]

The 14 lb Wolff springs are round wire and the 13 lb ISMI is flat wire. I tried a 12 lb Wolff in the gun with the 13 lb ISMI now in it. The 12 lb Wolff round wire spring was too light to allow the gun (slide) to close to lock-up/in battery on the vertical test of letting the slide close itself with the trigger pulled and the gun pointed vertically. The danger is the gun could fire out of battery or come out of battery too soon if the recoil spring won't adequately hold the slide and barrel fully in battery/lock-up. Plus, I've found that a very reliable gun can become not so reliable with the much lighter recoil springs - in other words, more susceptible to failures to feed, extract, etc., with the much lighter recoil spring. Your experience may vary.

Note that I am using the stock trigger spring and a lighter 4lb striker spring on a lightened Jager striker in a Vanek trigger. All the various springs have to be in harmony for the Glock to function properly. You can probably do a search on this forum and find more about that.

[Ssanders224]

My experience has been that wolf AND ISMI are unpredictable in weight and length.... I seriously got tired of it.

I switched to Sprinco's and it's like night and day. Every 13lb I have gotten has been exactly the same. They just seem to be nicer springs.

[Whitefish]

One thing I forgot to mention is that my production load with a 125 grain Zero FMJ bullet has made a 134 power factor out of my G34 and 133 pf out of my G17 at multiple crono'ed matches, so it is safely over the 125 pf floor for production, but not overly stiff by any means. You should be fine with either a 14 lb wolff or a 13 lb ISMI with a light load that at least meets the minimum 125 pf for production division in USPSA.

[Wesquire]

Well I was using a 14lbs Wolff spring, and I read the book "Glock in competition". I saw that Dave Sevigny and a few others have used 12&13lbs springs with 3-4 coils cut off. I tried it out (on my fairly worn Wolff spring) and now it doesn't lock up on the vertical test. I ordered a 12# Wolff spring, and I'm currently using the stock spring with about 3 coils clipped (it feels just a tad stiffer than the old Wolff). If the 12# doesn't work, I'll probably just get a new 14# because it has been 100% reliable. There really wasn't a problem with the 14#, but I'm new to pistol shooting so I wanted to try something else. My loads are about 128 pf 147gr

[Wesquire]

Also, I'm using the glockworx competition spring set