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Model 52 Spring Info

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targetbarb
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Model 52 Spring Info Empty Model 52 Spring Info

Post by DA/SA Sat Jun 24, 2023 4:25 pm

I am looking for the free length of an original recoil spring and main spring for a Model 52 S&W.

If you have any drawings, or possibly a new old stock spring please let me know.

Thanks!
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Post by targetbarb Sat Jun 24, 2023 6:42 pm

DA/SA wrote:I am looking for the free length of an original recoil spring and main spring for a Model 52 S&W.

If you have any drawings, or possibly a new old stock spring please let me know.

Thanks!
Numrich says main spring for a 41/46 can be used in a 52... Smith & Wesson 41, 46 Mainspring, New Factory Original Firearm Part for Sale | Numrich Gun Parts (gunpartscorp.com)

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Post by Froneck Sun Jun 25, 2023 6:03 am

If it helps I purchased 3 recoil springs for the 41 that are still new in the plastic bag from Wolff Springs (all they have available) in 6, 6.5 and 7 pound variable rate if my memory is correct. If it helps I can measure the free length. My spring tester is not complete yet, been working on my .22 conversion and will soon need the tester when I get to the point that my conversion needs recoil spring. Being the 41 supposedly has the a similar recoil spring I will probably buy a few 52 springs from Wolff since they might have different weights than the 41 springs I have. I can do some compression testing at that time if you still need it.

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Post by fc60 Sun Jun 25, 2023 11:27 am

Greetings,

I purchased a "new" recoil spring from Numrich Arms. It looks like the ones in the Model 52's I have access to.

So...

Free Length = 6.4"

Wire Diameter = 0.039"

Active Number of coils = 31

Outside diameter = 0.406"

Closed Ends on both ends.

I recall doing a Stress Analysis with an On-Line calculator a while back. The spring passed the test for Stress, unlike a 1911 recoil spring.

Cheers,

Dave
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Last edited by fc60 on Sun Jun 25, 2023 12:11 pm; edited 1 time in total (Reason for editing : More Data)
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Post by Froneck Sun Jun 25, 2023 12:28 pm

Interesting, what information is required of the spring to do the test? What information is returned from the testing? Why does the 1911 fail?

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Post by Wobbley Sun Jun 25, 2023 12:48 pm

The 1911 spring (and many gun springs) “fail” by taking a set from “surge”.  During a spring surge the mass of the coils continues to deform getting locally “solid” then expanding again.  These times at “solid” add up and if the stresses are high enough, the spring will accumulate set, weaken or even fail.  When the 1911 was designed this phenomenon wasn’t fully understood.
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Post by DA/SA Sun Jun 25, 2023 12:55 pm

Thank you Dave! That is exactly what I was looking for. One end on my original spring is slightly reduced for a coil or two to hold onto the guide rod.

Thanks to all for the other replies as well.


Last edited by DA/SA on Sun Jun 25, 2023 1:36 pm; edited 1 time in total
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Post by Froneck Sun Jun 25, 2023 2:41 pm

Wobbly; I understand what you posted. But why did a 1911 fail and 52 spring not? I'm thinking it was the free lengths vs the compression lengths. Being the 52 has all 3 what made the difference? Could it be the compression lengths used? I know little about the 52, haven't shot one for 30 years. Did have two 52s and a Colt National match 38. However now that I have been working on the .45 for at least 30 years I know that gun much better. The online drawing of the Mil specs for the 1911 compressed lengths is 3.72 and 1.81" However Wolff told me their measurement for listed spring weight was at 1.625", a friend has a spring compression tester that also indicates compressed length as 1.625". I would assume that the closed compressed lengths are about the same, doing some math using the dimensions shown in the online 1911 drawings I see the compressed length of 1.625" is about at the total rear travel of the slide. I'm therefore wondering what dimensions were used in the online test.

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Post by WesG Sun Jun 25, 2023 3:14 pm

Is the 'surge' a resonance thing? I've seen shock springs on my dirtbikes turn to a blur with the engine rev'd to the right RPM.

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Post by Froneck Sun Jun 25, 2023 4:45 pm

That may be true for the repetitive motion created in a dirt bike but the 1911 isn't a machine gun. The stated Failure implies that the spring will need to be replaced and a rate determined by the number of shots fired. Furthermore why would a 52 spring not fail? It's interesting to know how the "test" determined failure, what is failure, spring breakage or loss of strength? If there was failure somehow wouldn't the 52 spring fail at possibly a greater number of cycles?
 In addition would other gun springs fail? I have a AW-93, compression of the recoil spring is such that at complete rear travel of the slide the spring is compressed to dam near solid. I feel spring weight is too little but can't increase it by increasing wire size.
 I have never concerned myself with spring weight, I simply installed the spring that worked best. For the 1911 I have a complete set of Wolff springs that I use to test the pistol made by selecting the spring that worked best with the reloads and scope attached to the slide. However I have since gained some interest in springs due to the difference I have found in spring ratings. As mentioned online drawing gives 1911 spring compressed length at 1.81" Wolff states 1.625, Friend's compression gauge is at 1.625 and a well known gun builder said he made a compression tester by taking an average of ISMI springs and came up with 2.10". So if Wolff spring is 14lbs at 1.625, an ISMI 14lbs spring is at 2.10"??

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Post by Wobbley Sun Jun 25, 2023 6:15 pm

Froneck: My guess is that the 1911 was designed way back when the spring makers didn’t fully understand the dynamics of springs.  The 39 (which begat the 52) was designed post WW2 and by that time spring dynamics were better understood.

WesG :  what you see in a valve spring is just high speed spring actuation.  Spring surge is a phenomenon of the spring mass distribution and the spring rate.  A valve spring set has a very high spring rate compared to its mass.  Conversely a shotgun magazine spring has a low rate and it’s mass is very low.  Because of its length, it can be subject to surge.  Which is why shotgun tube springs can take a set or kink even if they never see more than two shells.
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Post by fc60 Sun Jun 25, 2023 6:29 pm

Greetings,

Back when I was undergoing my Tool & Die Maker Apprenticeship I got to spend several weeks on  the "Spring Bench". Here, I was trainied to fabricate a variety of springs.

I brought in a new Colt 45 ACP Government Model recoil spring and asked my Meister to show me how to make more of them. We ran the spring through the computer and kept getting "over-stressed, try a different wire diameter". Well that did not pan out as a thicker wire would not let the slide stop engage. The spring bottomed out.

We did put the factory spring on the load tester and it performed as per the USGI drawing I had. Hmmm, what gives?

A week later my Meister came to me with a suggestion. He had read about "Cold Setting" springs. Here is how it works. You wind the spring longer than what the drawing says. Temper it in the oven and once cooled you slip the spring over a guide rod and compress it bottoming it out (Cold Setting). The resultant spring is now shorter and interestingly the free length now matches the USGI drawing.

After a couple of custom wound springs we found a length that when tempered and Cold Set the spring now measured the parameters of the USGI drawing.

If you take the USGI Recoil Spring drawing dimensions and input them into Computer Design Spring Software it says over-stressed, try again. The S&W Model 52 recoil spring showed no errors.

In summary, the factory USGI recoil springs are starting to fail brand new. This is why I keep after folks to watch the "free length" of the spring as compared to a brand new one and change it out when the old spring shows appreciable shortening in length.

Also consider this. How many Bad Guys is the typical soldier going to dispatch with his 1911? If he bags 14 evil doers he deserves a new recoil spring from the Armorer. We Competitive shooters cycle that spring 180 times if you shoot 45 in CF and 45. After a couple of 2700's that spring is going to be a lot shorter. Bear in mind, I speak of shooting factory Hard Ball.

The drawing I supplied is based on Hooke's Law of springs. It is hard science and, provided the spring is designed to be not over-stressed, winding them per drawing pretty much follows the design.

Science is good, it should be your friend.

Cheers,

Dave
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Post by Froneck Sun Jun 25, 2023 8:24 pm

USGI drawing shows 13.55lbs +/- .60lbs at 1.81" compression. Looking at the amount the slide travels it is near 1.625" of compressed length. Most ball guns feel like the recoil spring is higher than 14lbs. So I think the additional travel increases the spring weight at near lock-back, however compression is linear, simple math without preload consideration is at 3lbs/inch (2.88 as per GI drawing). If 1.62 were used as compressed length that will be only 14.7lbs. But in today's shooting the "Ball" gun is a thing of the past, 230gr FMJ bullets are no longer required and reloads are acceptable. So I'm no longer thinking of "Ball" gun springs. Being now Wolff spring rating is at 1.625" of compression do "wad" gun springs shorten by the number of cycles? Adam's 1911 that he shot quite a bit when he was home and still shoots great after he being in the AMU 22 years, I shot it quite a bit too. Spring still feels the same as it did when I built it!
When I complete my spring tester I intend to make a fixture so that I can measure spring weight/travel distance on a complete 1911. Why?? I'm not sure yet but will have the capability. However I have found that I get be best group size (accuracy) with highest spring weight at closure that will function the gun so limit the main spring weight as much as possible. with lower main spring weight I can get better trigger action. Then there is the .22 conversion I'm making, eventually spring weights will need to be selected. So I'm interested in springs as used in pistols.

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