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Mainspring Weight


CzechShooter
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I know this has been a topic that has been hashed over several times in past years.  However, now that I am shooting the STI DVC O in 38 Supercomp (major), I want to know the significance in mainspring weight.  I already know that having a heavier mainspring ensures reliable cartridge detonation; but I've heard that the mainspring (weight) may contribute to how flat the gun shots as well; again I'm referring to open guns of course.  To further on, I have been told by a few open class shooters, that when they upped the weight of their mainspring, they saw and noticeable difference in dot tracking due to their gun's shooting flatter, no change in the recoil spring weight. 

 

Here's my theory: With today's lightened slides on most open guns, and the utilization of lighter recoil springs, having a heavier mainspring causes lightened slides to retard upon initial recoil, thus reducing muzzle flip.  

 

Right now I am running a 9lb recoil spring, and a 17lb mainspring.  I was thinking about trying out a 19lb mainspring to test this theory.  I also know that load development is a key component to a flatter shooting gun as well.  I am currently shooting Eley 124 grain 38 supercomp major ammo.  looking for some strong knowledge in this area.  Thank you. 

Edited by CzechShooter
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If you want to make your rig shoot “flatter” and not use the heavier main spring...try a flat base firing pin stop.

 

This will slow the unlocking and slide movement and make the gun flatter. 
 

This has been around a long time, so you can do a bit of searching and find lots of info on it.
 

 

Have fun.

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You tune your gun to your load with the recoil spring, mainspring and firing pin stop.  The idea is to retard the slide enough that the vertical impact area is not whacked when the slide reaches full stroke.  The harder the slide hits, the more the muzzle will rise and the slower your splits will be.

 

When I finished my 2011 Open gun I left the slide to frame fit too tight and I had ejection problems.  To cure I had to go to a 17 lb. mainspring, a FPS with the radius all the way up to the firing pin hole and a 7 lb. recoil spring.  I tried a 6 but it did not reliably strip rounds from the mag.  Even then 172 PF loads just dribbled out.

 

I decided to shoot the gun loose rather than trying to hone anything.  After about 7000 rounds I was happy with the ejection, everything was still tight, but I was unhappy with the way the pistol felt.  So I decided it was time to tune it to my load.

 

My load is a 115 HAP @1470 fps for 169 PF.  After trying a bunch of things I settled on an 8 lb. recoil spring, 19 lb. mainspring and a 'normal' Cheely radius on the FPS.  Muzzle rise was reduced and the gun shot softer.  A 9 lb. recoil spring also worked, but I liked the feel of the 8 better.

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8 minutes ago, BigBamBoo said:

If you want to make your rig shoot “flatter” and not use the heavier main spring...try a flat base firing pin stop.

 

This will not work on an Open gun.  You cannot change just one thing and expect it to work.  In addition, a flat bottom makes the gun way harder to rack on unloaded starts

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15 minutes ago, zzt said:

 

This will not work on an Open gun.  You cannot change just one thing and expect it to work.  In addition, a flat bottom makes the gun way harder to rack on unloaded starts


Huh....ran my 38SC that way. Guy I sold it runs it that way. He even set his other SC rig up that way.

 

yes, it is a bit harder to rack with the hammer down, buy unless you are girly, it is not an issue.

 

Again, this is not a new thing and has been around awhile....in fact you yourself wrote about it here some time ago.

 

Cheers

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Hello: Try it, you may like the way it feels. Firing pin stop contour can do alot on how it feels under recoil. Try some with a radius, flat and an angle cut. It all comes down on how it feels to you and hits on paper. For me I am using an angle cut firing pin stop, 17lb ISMI mainspring and a 8lb recoil spring. My loads are 115's at 171-173PF. My second favorite setup is the same springs and a radius firing pin stop. The flat bottom firing pin stop gives me too much flip. You could also try a 15lb mainspring but you may not get 100% ignition of the primers. These are all easy things to test and inexpensive to try also. Have fun with your testing. Thanks, Eric

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I run a 17 lb ismi mainspring and 7 lb ismi recoil spring with a nice smooth radiused FPS

I tried 15lb springs and i had ftfs, i even tried 17s with coils cut and 15s with coils cut. 

Once i moved back to a normal 17 mainspring everything started going boom again. 

I tried an 8,9,and 10 lb recoil spring and the 10 and 9 just felt too stiff

the 8 felt ok and the 7 felt the best

 

my load is 9.6 grains AA7 under 124 grain cast lead bullets at 170 PF

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3 hours ago, BigBamBoo said:

Huh....ran my 38SC that way. Guy I sold it runs it that way. He even set his other SC rig up that way.

 

I'm curious to know how you got it to run flat.  When I tried it I got a lot more muzzle flip with any assortment of springs.

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2 hours ago, zzt said:

 

I'm curious to know how you got it to run flat.  When I tried it I got a lot more muzzle flip with any assortment of springs.

Same. Flat bottom fps sucked imo. Dot lifted before the slide started moving. And unloaded starts sucked. 

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A heavier mainspring will give you a crisper trigger, and personally, I prefer a 19 lb spring with a radius on the fps (vs. 17 lb spring and square fps).  I know a lot of people like 17 lb mainsprings because it helps get the pull weight down.  But I find it gives a soft, spongy trigger that feels pretty crappy for a 1911.  I also don't like the impulse from a flat fps.  So, for me, the two combined make for a pretty awful combination.  Regarding the mainspring, a good smith can get you a sub 2 lb trigger with a heavier spring and it will feel a lot better than the same pull weight with a lighter spring.

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I completely agree Mr.Barone with respect to grip. If you're referring to Jerry Miculek, he's at a whole other level when it comes to shooting; that man is something I dream of becoming.  I believe that grip is everyone's nemesis.  I don't struggle that much with my grip, but if I can hone my gun to what I believe is perfect (which there's no such a thing LOL), I believe it will help my game.  Speed and accuracy in this sport is the name of this game;  with that being said, so are the basic gun handling fundamentals; grip, trigger and sight picture.  Thank you for your input sir. 

 

Johnny.  

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I am using a 15# main spring and 9# recoil spring with a angled firing pin stop in 38s/c. My load is 173pf. Over the years I have played with different combos

trying to by a score. What I do now is just pick a setup you like and shoot the crap out of it, stop chasing every little thing, work on the fundamentals. 

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