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How to determine recoil spring


deano2246

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Ok by the picture you can tell the gun has a VERY light slide, its a 38 super. I have been shooting the last owners loads (he only shoots steel so doesnt need to make power factor) he has been pushing a 115 grn bullet around 1050 FPS so making right at 120 power factor, and he has been using a 7 lb recoil spring. I need to get the speed up to around 1115-1125 FPS to get me safely around minor. I don't want to batter my frame and slide, how can I tell what spring I should use.

BTW I am brand new to open guns so all this is new to me.

Thanks

Kyle

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Here's the best piece of advice I've ever read (I know I read it on this board, but can't remember where, otherwise I'd give credit where it's due):

Bring the target in relatively close (five yards for me), take aim and fire two shots as fast as you can; don't even reacquire the sight picture. If the second shot is low, the muzzle dips as the slide slams home, you could use a lighter spring, if the second shot is high, you could use a heavier spring.

Of every method I've read, this one makes the most sense, in theory and in practice.

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  • 3 months later...

I've always picked the spring weight by doing double taps - you need an observer for this - if the 2nd shot goes lower than the first then a lighter spring is indicated. If the 2nd shot goes above the first, then a heavier spring is indicated. Goal is to get them on the same horizontal plane.

Give it a try, you might like it.

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Ok by the picture you can tell the gun has a VERY light slide, its a 38 super. I have been shooting the last owners loads (he only shoots steel so doesnt need to make power factor) he has been pushing a 115 grn bullet around 1050 FPS so making right at 120 power factor, and he has been using a 7 lb recoil spring. I need to get the speed up to around 1115-1125 FPS to get me safely around minor. I don't want to batter my frame and slide, how can I tell what spring I should use.

BTW I am brand new to open guns so all this is new to me.

Thanks

Kyle

Hey Kyle, if you don't want to beat up the gun, get that comp working as it should. Then spring accordingly. The Mainspring should be at least 2.5-2.7x the rate of the recoil spring. Remember the recoil spring only has one job, and that is to propel the slide forward with enough force to strip the next round out of the mag and chamber the round.

Slide velocity is not as influenced by the recoil spring, as much as it is from overcoming the force of the mainspring in cocking the hammer for the next shot.

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I have a similar setup to you and I'm running a 14 lb spring with major power factor ammo. Mine shoots minor just fine with a seven or eight pound spring. You are only bumping it up 75 fps, so you probably don't need to change anything.

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My favorite is a 10#, I find that my guns don't run a 100% with less than a 9# but the 10 seems to work best for me, according to the timer, repeating the same course of fire with different springs. I really don't care where the brass goes as long as it makes it out.

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I have tried the double tap route mentioned above and it works to some degree. Once you have done this test, I would pay attenntion to the dot. Does it goes up and down and does it move around? I think that a predictable dot is more important esp if it goes straight up and down and stay within the lens. When I did this, I selected a lower pundage recoil spring and then found that the dot was not predictable. I went up a pound in spring weight and have kept that.

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I started doing it back when there was just limited and open. Originally did it with the .45 w/open sights I shot in limited. Later, when I got the McCormick lower and ended up with an open gun it still seemed to work. Your results may vary somewhat, but, it will get you in the ballpark, spring wise.

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  • 3 weeks later...

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