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Old 03-21-2013, 01:26 PM
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Default Help with k frame main spring

Hi there, I have a new to me model 66-6 that was having light strike problems. I read that some people lighten the springs to make the action lighter by bending the spring.

I bought a new spring and screw, the spring is straight and the old one was really curved.
After putting in the new spring I am having problems with the trigger returning forward with the strain screw all the way in, if I back it out a little it works fine.

Do I need to bend my spring a little or leave the screw turned out some? Thanks in advance, Mike
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Old 03-21-2013, 02:10 PM
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Default Springs

Did you replace the mainspring with a factory S&W mainspring? From the description I am going to infer that the "cruved" mainspring was an after market spring- so it stands to reason that they replaced the factory rebound slide spring with a lighter spring also - so replace the rebound slide spring with a factory spring.....this way you are starting with a factory spec. spring set and let's see what happens from there. The mainspring screw should be tightened all the way down.. ( and loc tited)..always.

Last edited by loc n load; 03-21-2013 at 02:30 PM.
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Old 03-21-2013, 02:30 PM
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Quote:
Originally Posted by MA5177 View Post
Hi there, I have a new to me model 66-6 that was having light strike problems. I read that some people lighten the springs to make the action lighter by bending the spring.

I bought a new spring and screw, the spring is straight and the old one was really curved.
After putting in the new spring I am having problems with the trigger returning forward with the strain screw all the way in, if I back it out a little it works fine.

Do I need to bend my spring a little or leave the screw turned out some? Thanks in advance, Mike
I mentioned that gunsmiths that do a lot of action work on S&W revolvers learn to tune and re-shape the factory main springs. This is an involved process and must be done correctly over a wooden plug ( mold ) . If done wrong your throw away the spring and start over most of the time. This is not however something that you, for the most part, can do yourself unless you have somebody show you .

Therefore I would not recommend and in fact would advise not trying to bend your factory main spring. I wonder how you have determined if you are getting light hits or perhaps something else is going on. You mentioned the spring you took out was " really curved " so I sort of assume somebody got in their and worked on it. Whether the job was done right or not is hard to say even with a photo since there are many other things involved in setting up the hammer and spring. But it could be you had a nice action job there and somebody backed off or swapped out the strain screw and knocked everything out of kilter. Most of the time a spring is tuned then the strain screw is filed to a specific length to give the hammer the correct amount of pull and hit force. This screw is then Loctited for the needs of the shooter, i.e., type of load, primer and shooting sport or use.

You may just need to get a new full length strain screw and start over and screw it in and play with it until you get reliable ignition and trim it and Loctite. If that doesn't work and there are other problems then perhaps something else is going on here but I wouldn't presume to guess from here.

If you have a good quality trigger pull gauge or like instrument you can check the hammer pull which on yours without a target hammer should be 56 oz for 357 mag or 52 oz for 38 special.

Good luck
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Old 03-21-2013, 04:30 PM
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Thanks for the replies, I was having failure to fire on one of every 6 rounds of full .357 loads. .38 shot fine and the action and trigger seems like it had bee worked on. Very smooth. I bought a new ring and screw but now it seems very heavy. I am going to take it back apart to see if I did something wrong
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Old 03-21-2013, 05:46 PM
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When the trigger will not return, the rebound spring is not "balanced" to the hammer spring. The only way these two lightened springs work properly is with an action that has been honed/polished, reduced friction, reduced spring requirements. You can not just throw reduced power springs, or back out the strain screw, and have everything work correctly. For the lighter springs you must reduce the internal friction. I'd take the gun back to stock hammer/rebound springs and see how you like it and go from there.

Stu
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Old 03-21-2013, 05:57 PM
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You need to put the factory rebound spring in if you put a factory main spring in, that simple. it was probably changed to work with the bent main spring.
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Old 03-21-2013, 07:01 PM
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Ok great info thanks guys, I just put the bent spring back in with the filed down strain screw and it is working. Now I need a stock trigger rebound spring? And I can put the factory hammer spring and strain screw in and it should work? The action is smooth and light the way it sits now, no obviously it was worked on by someone. But I would like to use this for home defense and I don't want light primer strikes.. Thanks again
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Old 03-21-2013, 11:44 PM
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Default Springs

Yes - put all factory springs back in it, tighten the strain screw down all the way - then take it out and test fire it with your intended carry round. With all factory springs installed you eliminate all of the "unknowns" in the other springs.
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Old 03-26-2013, 08:54 PM
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OK...Thanks for all the help, here is an update.

I istalled a new main spring , strain screw and trigger rebound spring.
After inspection of the springs I removed, the main spring was bent, the strain screw was ground down and the rebound spring was shortened alot.

The action before was very light and very smooth, it shot .38 fine but not magnum loads,

Now with factory springs installed the action feels VERY heavy, single action not too bad but double action is a way harder pull.

So...Question? should I just leave it like it is or is there a way to make it lighter but still fatory reliable?
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Old 03-26-2013, 09:12 PM
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I appears you have a piece that has had an action job by someone who knew enough to tune the main spring and set it for a particular load. This set up obviously failed to meet your needs and therefore would not ignite mag primers.

Here is a suggestion that will cost you no more than a new strain screw. Put the mainspring and rebound spring back in the gun along with a new full length strain screw. Screw the strain screw in until you get ignition with mag primers like you want or if you know how to measure the hammer pull/load with a pull gauge set it for about 42 oz. BTW is this a target hammer ? if so add about 4 more oz of pull. With the new strain screw you can begin filing a bit off until you are close then when the gun shoots okay and the action feels better just Loctite the screw in place ( blue Loctite ) . It not a perfectly set up and cut to length screw but it will work and should stay there if you Loctite it correctly

Good luck
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Old 03-26-2013, 10:39 PM
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Is the "really curved" spring that was in the gun flat? Or does it have a raised rib in the center running down most of it's length?
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Old 03-27-2013, 07:49 PM
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Quote:
Originally Posted by tomcatt51 View Post
Is the "really curved" spring that was in the gun flat? Or does it have a raised rib in the center running down most of it's length?
Flat, just like the stock one only you can tell somebody bent it.

The OEM one that I ordered from brownells is straight with no curve at all
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Old 03-27-2013, 08:30 PM
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Quote:
Originally Posted by MA5177 View Post
Hi there, I have a new to me model 66-6 that was having light strike problems. I read that some people lighten the springs to make the action lighter by bending the spring.

I bought a new spring and screw, the spring is straight and the old one was really curved.
After putting in the new spring I am having problems with the trigger returning forward with the strain screw all the way in, if I back it out a little it works fine.

Do I need to bend my spring a little or leave the screw turned out some? Thanks in advance, Mike
Neither. Return the rebound spring to factory specs also. The strain screw is not there to allow a kitchen table trigger job. It should always be screwed down tight.

Whoever did the bad work on the 66 probably had reliability issues and got rid of it for that reason.

Let us hope that Bubba, the trigger job guy, did not damage the sear engagement in his zeal to do his kitchen table trigger job. If he did, you may end up with push off, in which case, let us also hope that Bubba, the trigger job guy, did not read on here about how you don't "need" the hammer block anyway, so you remove it to make the best trigger job.

If he did, let us hope when your revolver discharges when you do not expect it because a safety feature is removed that: (1) Bubba has plenty of liability insurance (not likely); and, (2) your muzzle is not pointed at anyone or anything you care about.
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Old 03-27-2013, 09:09 PM
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Whoever did the bad work on the 66 probably had reliability issues and got rid of it for that reason.

Let us hope that Bubba, the trigger job guy, did not damage the sear engagement in his zeal to do his kitchen table trigger job. If he did, you may end up with push off, in which case, let us also hope that Bubba, the trigger job guy, did not read on here about how you don't "need" the hammer block anyway, so you remove it to make the best trigger job.

If he did, let us hope when your revolver discharges when you do not expect it because a safety feature is removed that: (1) Bubba has plenty of liability insurance (not likely); and, (2) your muzzle is not pointed at anyone or anything you care about.


Pretty strong accusations without seeing the gun. As I noted earlier there are plenty of comp or race guns built and tuned for a specific load a load to compete with. Another load with a magnum primer may not ignite but this has nothing to do with the competency of the gunsmith. Maybe the gun has been hacked but I would not suppose it base on what we have heard and certainly not seen so far.

I wonder if the OP would comment and tell us if this main spring resembles any of the three in this photo. The spring on the right is a factory K. The others have been reworked and tuned by a very highly respected Smith & Wesson gunsmith who may or may not have done them on the kitchen table.

http://smith-wessonforum.com/attachm...1&d=1364432705
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Old 03-28-2013, 05:12 PM
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Quote:
Originally Posted by garbler View Post
Whoever did the bad work on the 66 probably had reliability issues and got rid of it for that reason.

Let us hope that Bubba, the trigger job guy, did not damage the sear engagement in his zeal to do his kitchen table trigger job. If he did, you may end up with push off, in which case, let us also hope that Bubba, the trigger job guy, did not read on here about how you don't "need" the hammer block anyway, so you remove it to make the best trigger job.

If he did, let us hope when your revolver discharges when you do not expect it because a safety feature is removed that: (1) Bubba has plenty of liability insurance (not likely); and, (2) your muzzle is not pointed at anyone or anything you care about.


Pretty strong accusations without seeing the gun. As I noted earlier there are plenty of comp or race guns built and tuned for a specific load a load to compete with. Another load with a magnum primer may not ignite but this has nothing to do with the competency of the gunsmith. Maybe the gun has been hacked but I would not suppose it base on what we have heard and certainly not seen so far.

I wonder if the OP would comment and tell us if this main spring resembles any of the three in this photo. The spring on the right is a factory K. The others have been reworked and tuned by a very highly respected Smith & Wesson gunsmith who may or may not have done them on the kitchen table.

http://smith-wessonforum.com/attachm...1&d=1364432705
No the one that was in there looks different than all of them, the one on the right is like the one I recieved from brownells.

The way it sits now it seems to work fine with all the factory springs installed but its way heavy. I ordered a wolff LE spring and rebound spring pack, it is suppose to lighten it up some but still retain reliability.

I dont think this was done by a total hack, the action was smooth as glass and nice double and single action .

Like I had said, it shot target loads fine and had a few light strikes on magnum loads.
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Old 03-28-2013, 10:19 PM
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Quote:
Originally Posted by MA5177 View Post
No the one that was in there looks different than all of them,
Does it have all it's arch in the top 1/4 of the spring? The Jerry Miculek, Bang Inc., kit spring looks like that.
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Old 03-29-2013, 08:50 AM
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Default Here it is

This is the one that was in there with the ground down strain screw and shortened rebound spring
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Old 03-29-2013, 09:16 AM
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That really looks like it should be ok in a "tuned" gun. Might try replacing the strain screw with an 8-32 socket set screw and use that spring. The socket set screw will allow adjustment. Screw it in until you get reliable ignition shooting DA.

A 3/8" long set screw should be right. Loctite it after you get the gun running. Same proceedure will work with your Wolff spring. Then you can play with rebound springs. How much rebound spring you need is proportional to how much mainspring you need for reliable ignition.

You can (pretty) easily get a sub 8 lb DA pull (with a stock hammer) that will fire the hardest primers.

What's a Wolff LE spring and rebound spring pack? Never heard of it. Got a link?
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S&W-Smithing Thread, Help with k frame main spring in Ammunition-Gunsmithing; Hi there, I have a new to me model 66-6 that was having light strike problems. I read that some ...
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