(Another) 1911 Recoil Spring Question

[g.willikers]

Another consideration is what can happen when a tired recoil spring gets "saggy."
(High tech term mostly used by high class spring design engineers.)
It can turn into a solid bushing, instead of a spring, making life hard for the parts involved.
There's lots more involved with gun designs than is first apparent.

 

[DaleA]

Well I think it’s pretty clear that Nick’s 1911 was getting beat up by the heavy recoil spring and that Nick got beat up a little by asking the question about the heavy recoil spring but no worries---both seem to be up to taking it and other folk like me that lurk around the edges got a little bit more education about this hobby we like so much.

Thanks again to Nick for asking about heavy recoil springs and for everybody that provided information.

Personally I think I’ve just been kind of lucky with my guns, I haven’t had to replace the springs yet. The guns have seen some 230 grain factory loads and some 230 grain military surplus loads but mostly powder puff bullseye loads.

 

[Aguila Blanca]

Rearward slide travel stops when the lower end of the slide comes into contact with the frame abutment otherwise known as the vertical impact surface,note that the guide rod collar serves as a shield from direct impact.

The frame abutment is, as you describe, the vertical surface against which the recoil spring guide flange seats, and it is the frame abutment that stops the slide's rearward movement.

The vertical impact surface (VIS) is the smaller vertical surface farther aft from the frame abutment, and the forward side of the frame bridge/barrel bed. The slide never contacts the VIS. The VIS is what stops the barrel, when the vertical surface at the rear of the underlug hits the VIS.

They are not the same thing.

Another consideration is what can happen when a tired recoil spring gets "saggy."

It can turn into a solid bushing, instead of a spring, making life hard for the parts involved.

Not possible. Fatigue in a coil spring cannot add material, and cannot cause spring bind. The only cause of spring bind is a spring that's too long.

 

[Nick_C_S]

DaleA: You're welcome. I've learned a lot too. The responses to my original post turned out to be even more valuable than I had hoped. This has been good.

 

[Mike38]

Nick, I'm surprised the 200 gr LSWC light loads worked with a 22lb spring. For loads like that, I use a 15lb or 16lb spring.

 

[Clark]

Notice the two sources of hysteresis in my 1911 slide force; 1) Friction, 2) cocking the hammer.

I took that data points manually with a Wagner force gauge and dial indicator.

 

[KyJim]

Clark --

If you posted to make some of us think we are stupid, you succeeded, at least with me. The graph simply seems to be how much force is necessary to rack the slide backward, with and without first cocking, at a particular point. Obviously, the slide requires more force initially to rack backward if the gun is not cocked. When the slide then moves forward, it does so with less force due to friction.

I had to look up the term "hysteresis." As I understand it, the lag in the slide moving forward due to other forces (friction) is the slide's hysteresis.

 

[Aguila Blanca]

I don't understand at all what Clark's graph is trying to show, or how it in any way relates to the topic of this thread. Further, the graph is for a Commander, whereas the pistol under discussion is a standard, 5-inch, full-size 1911. The orifginal M1911 had a 14-pound recoil spring, and most manufacturers today seem to have standardized on a 16-pound recoil spring. The standard recoil spring for a Commander is an 18-pounder.

We seem to be getting farther off the track as the discussion progresses.

 

[P71pilot]

So the graph is saying that with the slide back 2.2inches, the slide contains 60lbs of energy? I don't think even with the mass of the slide that is being forced with 16lb it could contain that much energy

 

[Clark]

Energy is equal to the integral of force over distance.

If that were ~25 pounds and ~2", that would be ~ 4 foot pounds of energy.

When calculating momentum of weight and velocity of bullet and gas and resultant reaction of slide relative to frame, half the energy and/or momentum gets lost. That is because the frame, hand, and forearm also get accelerated.
So we only need half the spring we would calculate we need based on bullet and gas momentum relative to the frame.

I can see I calculated that and posted it on usenet in 2001
https://groups.google.com/forum/#!topic/rec.guns/rphahGf850w

That was my calculation of far cases fly.
I had to revise it in 2003 for that limp wrist effect.
https://groups.google.com/forum/#!msg/rec.guns/zfECQTdlFok/vVdOeWJpVcwJ

I had to call up my father to ask about the gravity equation. Here is pic by a professional photographer on staff of my father designing a machine gun. That gun never made money and the patent has expired. But the pic was during the enthusiasm phase of the project. On his window they had little metal models made of guns that DID make money.

 

[Hunter Customs]

I've heard the term "forward battering" and that doesn't sound good. Is this really a thing? If so, what is being battered? And how serious is it? I don't want to beat up my guns.

Yes there is such a thing as forward battering, I've written about that on this forum in the past.

There's three parts that takes the brunt of the forward momentum when stopping the forward movement of the slide.

They are the slide stop pin, the lower lug of the barrel and the frame itself. The radial lugs of the barrel and slide along with the barrel hood (depending on fit) are involved also but not to the same degree as the other parts mentioned.

Keep in mind the frame is the softest part out of the three, it will be between 24-28 in hardness on a C scale.

Those shooting the gun games go the other way, using lighter recoil springs to help them in tracking the sights better.

Best Regards
Bob Hunter

 

[polyphemus]

So we only need half the spring would would calculate we need.

Now that! makes a lot of sense.

 

[Clark]

OK, I fixed it.
So we only need half the spring we would calculate we need based on bullet and gas momentum relative to the frame.

 

[Rinspeed]

The recoil spring has very little to do with slowing down the reward momentum of the slide compared to the main spring in a 1911. In fact you can shoot a 1911 without the recoil spring and do little damage. Too strong a recoil spring will do much more damage than one that is too weak.

The recoil spring's main purpose is to return the slide into battery. Not only that but as you increase the forward speed of the slide you run a much greater risk of the mag springs not being able to keep up.