Security Six Mainspring Length?

[Carry_Up]

If someone happens to have a real Security Six mainspring in their parts drawer, I would like to know the uncompressed length of the spring, or the number of coils, or both. Specifically, I'd like to know if the Security Six mainspring is longer than the GP100 style springs.

Thanks for checking.

-CU

 

[Alpha426]

Hammer spring length (uncompressed) = 1.75 inch

17 Coils

 

[Carry_Up]

Thank you. I measure 1.75" on the 14 pound GP100 spring as well, with 19 coils. The 12 pound GP100 springs go up to 1.9". This is of interest for those who want the correct Security Six mainspring. I believe the factory Security Six mainspring is 16 pounds, but most people report satisfactory results with a 14 pound spring. That means that a GP100 14 pound (reduced power for the GP) will work.

The Security Six hammer/strut geometry is different than the GP and I see that having enough pre-load on the mainspring is important. If the hammer is pulled gently away from the frame about 1/8", and remains there without returning to the frame, there is insufficient preload on the mainspring. In my opinion, the spring has an insufficient number of coils and/or the overall weight is too low.

Security Six firing pin protrusion is just shy of .050 on a good day, so careful selection of reduced power springs is important.

-Carry_Up

 

[Thel]

Carry_up, the information is interesting. I wonder what the length and # of coils is for the 14 lb Six Series spring from Wolff or if it is the same spring as the GP/SP mainspring? I think spring length probably has more importance than # of coils as the wire diameter could be different or the spring metal composition slightly different to influence pull weight. When I get the Wolff 9, 10, 11 and 12 lb springs will have to measure them. The preload also would have a bearing on the evenness of the double action pull.

 

[Carry_Up]

For some reason Wolff cannot manage to ship a couple of springs in less than 30 days. When they arrive I'll post the length/coils on a Wolff design Security Six mainspring.

One way to increase spring weight is to use thicker spring wire. Another way is to lengthen a spring using the same diameter wire. More coils usually result in a more consistent DA pull (which is dependent upon hammer and strut geometry) but of course you do not want the spring to stack (coil bind).

The GP100 14 pound reduced power spring fits and works fine in the Speed Six. Preload is good and the hammer returns to the frame (test above). Overall feel when cocking the hammer is smooth so no complaints.

-CU

 

[Thel]

Took a look at a 14 lb Wolff Six Series spring. The length is 2.15" with 22 coils. A Wolff GP/SP mainspring that is 11 lbs is 2.04" and has 20 coils. A 9 lb mainspring is about 1.83" long and has 21 coils. The lengths may be off a few 0.001's as measured in the packaging with a Dillon metal calipers. Reticent to open the packages as once upon a time had lots of springs but knew not what the ratings were or where used in particular. Also, it appears the wire diameter varies somewhat. When I get my Speed Six back from the gunsmith will try the 11 lb mainspring out of curiousity to see if it works. As I recall 20+ years ago when I had a Sec. 6 used the Six Series 14 mainspring and trigger return and did not notice much reduction in trigger pull for the effort. Switched to a Bullseye spring kit but the never specified their spring ratings. The trigger was noticeably lighter without misfires and even throughout. If I recall one thing Grant Cunningham mentioned when tuning trigger pull weights there is a balancing act between trigger return and mainspring weights to get it all working in harmony.

 

[Carry_Up]

Thanks for the info Thel. One thing you are seeing with all the spring weights and types is that for a given application - i.e. a GP mainspring - lighter weight springs often are longer with more coils. However the lighter springs also use smaller diameter wire, so there is another balancing act to achieve a smooth spring rate distribution for various spring weights.

Also remember that all springs take a "set" soon after they are installed, which shows up as a shortening of the overall uncompressed length. That's normal. So a spring that has a marginal pre-load when new might have no preload at all after taking a "set". The Security Six I have on my bench at the moment had intermittent light primer strikes. But it was obvious that someone had cut a few coils off the original spring. Sure thing the trigger pull is lighter, but so is the primer strike. Cutting coils is a bad move in most cases.

The Six series uses a torsion spring inside the trigger housing. Fortunately Wolff offers a reduced power torsion spring for that purpose. Here is some interesting spring information showing various types and shapes.
http://www.planetspring.com/pages/types-of-springs-custom-springs.php

carry_up

 

[Thel]

Thanks for the spring info, Carry_up. Interesting. Usually, a cut spring is a "home gunsmith" operation. Most gunsmiths (at least the ones I have dealt with) seem to put the spring on a lathe and turn down the outside of the coils so the length remains but less tension. Not saying I recommend it but that is what they do. It is interesting that one sees occasional comments on leaf vs. coil springs and smoothness of the action (Ruger vs. some S&Ws/Colts) but the über expensive Korth uses a coil mainspring.

 

[Carry_Up]

I received a Wolff reduced spring package that includes a 14 pound "reduced" mainspring and a reduced trigger spring. The mainspring was as above 2.16" uncompressed with 22 coils. The reduced power trigger spring is worth the money as the trigger assembly moves smoothly as long as no burrs are hanging it up, and as long as the transfer bar and hand move smoothly in their channels.

The mainspring is another story. If this 14 pounder is "reduced" I'm afraid to look at what they call the factory standard weight. With the reduced 14 pounder in place I almost need vice grips to cock the hammer. DA pull was 12 pounds and that is unacceptable. I put the GP100 factory mainspring back in with the following results: DA pull 8 - 8 1/2 pounds, SA pull just over 3 pounds. That's what I would expect from a revolver that has had all the filings emptied out and the sharp edges removed. So its out to the range to see if ignition is reliable.

-carry_up

 

[Thel]

The stock mainspring is 16 lbs. Wolff does not offer one but does offer a 17 lb one. I vaguely remember from the 1980's when I had a Sec. 6 before tuning and changing springs double action in the 13's. Single action was 5.5 or 6 lbs as I recall. The double action is about what I had on a stock SP101 before tuning and springs. Ruger does like stout trigger pulls.

 

[Carry_Up]

A few extra words on the subject - one of my favorite I guess. Referring to the "reduced power" 14 pound mainspring, part #17614 - the uncompressed length is too long. That means that a good portion of the rated 14 pounds is already present in the pre-load. When the hammer is down you have already stored maybe 5 or 6 pounds of energy.

You can see how juggling all the factors is tricky. That 5 or 6 pounds does not translate directly into trigger pull weight. But with that kind of pre-load, the hammer won't even think about moving until you approach a relatively high trigger pull. At that point the hammer will "snap" all at once. You don't get any trigger feedback at all. The hammer just snaps all of a sudden. Obviously that is not the correct spring for the job.

So after trying a dozen or so springs in my drawer, it looks like a factory standard weight GP100 spring gives you a good compromise. Ideally it should have one or 2 more coils, but I'll take it anyway.

Of course nobody thinks they will get a finely tuned target trigger on a new gun these days. It used to be that a S&W revolver had an excellent SA pull right from the factory. You didn't need to touch it. These days production guns, including the new S&W's, have internal parts that are so rough and crude that the gun won't work at all with standard weight springs. Heavy weight springs are required just to make all those sharp, rough and incorrectly machined parts move.

Truthfully, I'd rather be out shooting than researching what spring goes with what gun. But that's the way it is.

carry_up