Why isn't there more "progressive springs" used in guns?


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twoblink
October 15, 2004, 01:20 AM
Like cars etc.. It seems like progressive springs are a good idea, and would work well in guns, so I'm wondering, why aren't progressive tension springs used more often in guns?

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Hawk
October 15, 2004, 07:07 AM
From Wolff Gunspring's FAQ:
The choice is often very subjective. Variable recoil springs reduce the battery load values with increasingly greater recoil load values. This results in easier unlocking, improved recoil energy storage, dampening, feeding, breaching and lockup. Variable recoil springs are particularly beneficial with compensated pistols and when using light target loads where less recoil energy is available. Conventional recoil springs are particularly beneficial when shooting heavier loads where keeping the slide closed as long as possible is desired. The "correct type" of recoil spring is best determined through experimentation and your own personal preference.
I'm no expert so couldn't address WHY keeping a slide closed as long as possible is a good thing with heavy loads...

twoblink
October 15, 2004, 08:35 AM
because work = F over Time, and so when you increase Time, and maintain the same F, then your work is decreased... Thus keeping it closed as long as possible, reduces the work done on the gun.. (or in laymen's terms, beating up of the parts)

FNFiveSeven
October 15, 2004, 01:00 PM
Work = Force * Dist which does not equal Force/Time.

ShaiVong
October 15, 2004, 10:18 PM
Work is Force over distance, power is work over time, right?

Amish_Bill
October 15, 2004, 10:58 PM
Try this -

While the barrel is locked to the slide & frame, recoil energy is spread over the entire mass of the gun. When the barrel unlocks from the frame, only the barrel and slide are absorbing the recoil energy.

heavy load into full mass = lower acceleration & overall velocity.
heavy load into reduced mass = faster acceleration of the slide and a sharper thump when it hits full retraction.

It's just a theory.

Larry Ashcraft
October 15, 2004, 11:01 PM
A couple of years ago, Richard Heinie had a bunch of progressive springs for sale "cheap" on the 1911Forum. I PMed him and told him I might be interested, then I asked my 'smith about getting them. He said he didn't like them, so I PM'ed Richard back and told him what my 'smith said. Here's what the man said:
Larry,
I don't use them either. These are left over from the days when I sold Comp Kits. We used these with 10MM Heavy Loads. I use nothing but std. power springs. Listen to your gunsmith.

Richard

FNFiveSeven
October 16, 2004, 01:02 PM
ShaiVong,

Work (aka energy) is force times distance, the greater the distance with any given force, the more work done, lifting a 5 kg weight abover your head is 5x as much work as lifting a 1 kg weight above your head. Power is work over time, i.e. the rate at which work is being done.

FNFiveSeven
October 16, 2004, 01:15 PM
Amish Bill,

The total recoil energy can only be changed by changing the mass of the gun (assuming the same load). A semi auto and a revolver of the same mass shooting the same load have the same recoil energy. However, the semi auto feels less because the time over which the energy is delivered to your hand is extended, causing the power to reduce. The spring slowly delivers the recoil energy to the frame (and then to your hand), whereas the revolver delivers any recoil instantaneously.

I think progressive springs are a great idea in guns, and here's why. Let's say you're shooting you 1911 with a particular load, say a 185 grain low recoil handload. Because of the low recoil impulse, you need to use a light spring to allow the slide to move all the way back, if you use a heavier spring, the slide will short stroke on you and the gun jams. But now, let's say you shoot a +p 230 grain load with the same gun. Well now, that light recoil spring isn't enough as the slide comes flying back and batters the frame, wearing it out and giving you a light push followed by a sharp thump as the frame instantaneously dumps all of its energy into the slide (and you hand). With a progressive spring, you get the best of both worlds. The first part of the movement is light, so that you can shoot your light 185 grain loads without short stroking. But near the end of its travel, the spring stacks up to 20, 30, and 40 lbs so quickly that even when you switch to your +P 230's, the slide still doesn't smash into the frame, greatly extending the lifetime of your frame and greatly reducing the perceived recoil. Of course, the best way to minimize felt recoil is to use the one perfect spring for each load, but that's a pain in the neck and the progressive spring is an excellent compromise for a gun that needs to digest whatever it's given.

JohnKSa
October 16, 2004, 02:05 PM
Be very careful about using non-factory progressive recoil springs or lighter than normal recoil springs in Glocks.

The slide is held forward in battery by the recoil spring, but there's also pressure to the rear from the striker spring. When the trigger is pulled, this applies rearward force to the striker which in turn pushes harder on the slide. With a light or progressive recoil spring (particularly with an 8lb or higher connector) it's possible to push the slide partly out of battery with trigger pressure. That's not such a good thing.

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