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ISMI weight vs wolffe weight


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For some reason I have it stuck in my head that I read somewhere, a gun will give similar performance with a lighter ISMI than it will with a Wolffe. For instance a gun that will not run anything lighter than an 11 lb Wolffe can run a 9 or 10 ISMI.

I couldn't think this would be correct for a conventional vs an ISMI, but maybe for a variable against the ISMI.

I'm in the process of putting together an order for some new springs and am trying to decide on wieghts and company.

Currently, I'm using a stock recoil assembly in my G-34 and a 10lb variable (it feels a little slow, but in the past hasn't worked with anything less) in my 1911 9mm, with a 17lb mainspring but I'm thinking about trying a 15.

Suggestions would be appriciated.



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I can only speak from my personal experience on this. I have found that the ISMI springs keep their "static length" and strength much longer than the Wolff or ANY OTHER springs I have ever used.............. and I have used just about everything on the market, at one time or another. Because of the ability of the ISMI to maintain it's original strength for such greater number of cycles, a lower strength rating works for me better than the similar ratings from other brands, because the other brands loose strength so much sooner than the ISMI. In other words, an ISMI 15 pound recoil spring STAYS 15 pound (or darn close to it), while a 15 pound Wolff (or anything else I have used) starts out at 15 pounds, but very shortly "settles in" at 13 or 14 pounds after being compressed for a while in the firearm, or from being used for a short while.

As I said, I can only speak of MY EXPERIENCE, and I am NOT a gunsmith. I have run EXCLUSIVELY ISMI springs in all my 1911s for quite some time, and think they are the best. Marc Cosat (owner of ISMI) is a great guy, quite knowledgeable, and quite willing to share that knowledge. Give him a call and discuss your question(s) with him. I guarantee you that no matter how much you might know, you will learn SOMETHING from your conversation with Marc.

Best of luck,

Jeffro (Jeff)

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The key is what amount of force is being applied when the gun is in battery and when it is at full recoil. The printed or stated weight of the spring is only applicable only if you do not cut or alter the spring. So make or buy a spring tester :D

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