Why is clipping off coils in springs considered bad?

[ken158]

I have always wondered how polishing the leaf style mainspring helps?

Kind of like putting chrome on your car engine - might make you think it is faster... and makes you believe you are smarter than the engineers that designed the gun!

 

[Printer]

I must admit I've seen some interesting answers to the initial question here, so interesting, I'm even confused. First lets deal with cutting coils off the rebound spring. There was a time many years ago it was acceptable to clip a couple of coils off the rebound spring. Then, because of liability, it wasn't allowed. Cutting coils off the rebound spring can cause a couple of problems. One which can be REAL serious, it overrides the number one safety (the hammer seat on the rebound and rebound seat on the hammer). During NORMAL functioning, if the gun were dropped in the single action mode, and the hammer fell, the rebound would go forward faster (propelled by the rebound spring) than the hammer could fall and the rebound seat on the hammer would fall on top of the hammer seat on the rebound and the gun would not fire. By clipping coils on the rebound spring you retard the forward movement of the rebound thereby overriding your number one safety. The second problem caused is the trigger won't recover forward.
Someone mentioned "push off". Push off has nothing to do with cutting coils off the rebound spring. Push off is the relationship of the bevel on the trigger to the cocking notch on the hammer. The correction for push off is to sharpen the bevel on the trigger. (NEVER touch the cocking notch on the hammer).Place the trigger face down on a mat and using a 6" stone sharpen the bevel on the trigger 2 strokes, re-assemble and try it. If push off is still there try two more strokes. I hope this info was helpful. If your still not sure about clipping coils contact me and I'll try to be more helpful.
Bob St.George
Chief Armorer Instr. S&W Armorer School (RET.)

 

[Gaffer23]

The flattened (in thickness) coils at the ends of properly formed coil springs are referred to as "dead coils" and affect the function of the spring. If you're going to shorten springs, you really should restore the dead coils.

If you clip a rebound spring and put it in with the raw, clipped end against the frame stud instead of the rebound slide, it's possible for the spring to slowly escape. I've never seen it, but it's possible. This could have embarassing/fatal results.

I can believe this. I've cut a coil or two off a spring in my past and I never could just leave the cut alone. It seemed to me that the cut was at a point in the spring cant (the angle of the spring coils) and that there was really only one initial point of the spring contact with whatever it landed on. My ideal fiddling was to try and gently coerce that last coil into a position so that most of it contacted the mating surface. And, occasionally, that meant dressing up the end with a 1" belt sander to flatten everything out. Heating up the last coil would probably make the reforming easier, but it would also truly make it a dead coil. Nevertheless, I believe just cutting off a coil or two without come sort of redressing isn't what I'd recommend.

My two cents - not worth much.

 

[OMCHamlin]

Regarding polishing leaf type mainspring surfaces- if engaging surfaces are over-polished, you'll remove the small microscopic grooves that retain oil, leaving a metal to metal surface. the coefficient of friction w/o lube is significantly higher.
And... don't grind down the leaf spring tension screw residing in the bottom front of the frame's grip. It is about the quickest way to induce single action pushoff.

Your response indicates that you may not fully understand the question, let me offer up a point or two, the act of thinning the sides of the leaf spring is known to lighten the spring tension of said leaf spring, thus reducing the overall pull weight, particularly noticeable in double action cycling. This does induce the risk that you can get light primer strikes (misfires), JUST the same as clipping coils off of a J frame coil mainspring. You should consider the end use of the firearm under modification; a target pistol that misfires from time to time at the club is not necessarily as life impacting as the 640 that you just got through clipping 4 coils off of (I can't believe I saw that exact number quoted above in this thread, brother, YOU are making an epic mistake!), and you are pumping gas into your Lexus at a local stop and rob, while a pair of brothers roll up on you intent on robbing you and stealing that smooth ride of yours. You skin that little pocket rocket, smoothly come up to a contact point shoot and... click!...click, click, click... Yeah! hey yo, man, you better hope that thing had a good dehorning, because guess where it's going to end up right before the bludgeon you to death with a tire iron??? Anyhow, go ahead, take 4 or even 5 coils off, it's smoooooth, right?

 

[thefresh2o]

Lots of reading here. Lots of sound thinking, some... Notsomuch.

Another way to lighten a spring without clipping is to mount it to a mandrel in a drill and spin it over a stone, removing material and lightening the spring. This maintains the stack up and rate of the spring.

The advent of good aftermarket (Wolff, natchurlich) springs has made life easier, but this ongoing war on terror sure has made importing parts from the USA a lot harder.

 

[tomcatt51]

Another way to lighten a spring without clipping is to mount it to a mandrel in a drill and spin it over a stone, removing material and lightening the spring. This maintains the stack up and rate of the spring.

Doing this reduces the springs rate, lbs/in. Because the rate is reduced, the springs' preload (lbs) is decreased. Same amount of compression (free and installed lengths haven't changed) but rate is reduced so less preload, lbs.

The problem with grinding down the springs' OD is how easy it is to overheat the spring during the process.

 

[usnrigger]

well, i have no problem clipping coils on the recoil spring given its a target only pistol. serious social work guns need factory unaltered parts "period". You can clip up to four coils of factory spring if done properly and other tuning is made throughout to compliment each other. Im not saying you should but it can be done and function properly

That being said i normally only clip one or two coils, and you don't need aftermarket springs you can tune every factory spring to your needs.

USNRigger

 

[Wilson Custom Guns]

In reply to the question of strain screw length. In the Armourer School we were told that you should file the tip of the strain screw to get the correct hammer pressure, but never back it off. If my memory is correct the hammer pressure can be reduced in this way until you get a minimum of 3 1/4lb for a "std" load like .38spl and 3 1/2lb for a magnum. However depending on the spring profile you may get "knuckling" of the hammer link before you get that light.