351c Mainspring Weight?

[Ken6PPC]

Does anyone know what the weight of the OEM mainspring is in a 351c?

Trying to get a better pull while maintaining reliability. I tried a lighter weight MS I had lying around from a previous job on my 642 (don't know what that spring's weight was...), and reliability suffered. So, I know a really light MS won't work for this rim fire.

I already polished the hammer and rebound spring housing, and installed a lighter weight (14 lb. I think) rebound spring.

In case the OEM MS weight is unknown, has anyone successfully improved their 351c trigger pull using a known MS weight?

 

[357-RevolverGuy]

Personally I wouldn't mess with it. Rimfire revolvers are notorious for light strikes/failure to fire with lighter springs. I have own a 351c now for almost 10 years. It feels like over the time of a few months of range sessions the trigger pull smoothed up on its own.

 

[Ken6PPC]

Personally I wouldn't mess with it. Rimfire revolvers are notorious for light strikes/failure to fire with lighter springs. I have own a 351c now for almost 10 years. It feels like over the time of a few months of range sessions the trigger pull smoothed up on its own.

Yeah, I get it. I know rimfires require more hammer force than centerfire.

However, I still would like to try a lighter MS in my 351c, and I am hoping someone here can share their own experiences and results.

I'm SURE I am not the first one to want to lighten a trigger for a 351c, but I haven't had any luck searching this forum for MS weights.

If someone has some personal experiences with lighter MS weights for a 351c to share, please let me know. PM me if you don't want to post your experiences here in this thread.

 

[Alk8944]

Wolff Gunsprings has this information on their web-site. Well, at least I thought they did! No springs for J-Frame guns at all, just K, L, N Frames. it has been a while since I needed anything for J-Frames. Call S&W Customer Service and they may be able to help. 800-331-0852. Apparently the move to Tennessee has slowed things down a bit.

 

[Racer X]

Ask these guys. I have a bunch of their kits to install in Glocks, a Winchester and a Taurus S&W J Frame Trigger Job - Smith and Wesson Trigger Spring Kit

nevermind. Says it won't work for a rimfire J frame. I'll leave it up for general info.

 

[Ken6PPC]

Posting for future reference...

I spoke with a guy I know here locally who has done a LOT of trigger work on S&W J frames, and he says he thinks the 351c uses the same MS as a 317.

Wolff lists the MS for a 317 as 12 lbs.

I ordered some springs, and will update this to post my results.

 

[Shibadog]

You find something that works let us know. I’ve got a 351PD that I love, BUT the trigger pull DA is very stiff, and I’ve had two gunsmiths (one of whom is nationally known for his custom S&W’s and Rutgers) both tell me they won’t work on rimfire revolvers because of reliability issues. No matter how good the trigger if it doesn’t go “bang” everytime you got an unhappy customer. I’d love to get the DA down to 8 lbs or so, but I’m not at all sure that’s even possible if you want a reliable piece. FWIW, they “do” smooth up fairly well with use-mines had the best part of 1k now and is a lot nicer than when new.

 

[Ken6PPC]

You find something that works let us know. I’ve got a 351PD that I love, BUT the trigger pull DA is very stiff, and I’ve had two gunsmiths (one of whom is nationally known for his custom S&W’s and Rutgers) both tell me they won’t work on rimfire revolvers because of reliability issues. No matter how good the trigger if it doesn’t go “bang” everytime you got an unhappy customer. I’d love to get the DA down to 8 lbs or so, but I’m not at all sure that’s even possible if you want a reliable piece. FWIW, they “do” smooth up fairly well with use-mines had the best part of 1k now and is a lot nicer than when new.

Yeah, I smoothed mine out a lot before even firing the first shot (shot it today, in fact). I used an India oilstone to polish both sides of the hammer, and both sides and the bottom of the rebound slide.

Even with the heavy trigger, it didn't shoot badly at all! I really like this little pistol. Light as a feather, and hardly any recoil. I shot Speer Gold Dots today, and plan to try some Federal Punch when I can find some. Ballistic Gellatin tests are encouraging for those two rounds.

[ame="https://www.youtube.com/watch?v=v2XwUlCWqLE"]https://www.youtube.com/watch?v=v2XwUlCWqLE[/ame]

[ame="https://www.youtube.com/watch?v=NMkp2m6ZuIc&t=315s"]https://www.youtube.com/watch?v=NMkp2m6ZuIc&t=315s[/ame]

Good or bad, I will report what I try and what I learn. I think there HAS to be some spot where the MS is strong enough to be reliable, yet better than stock! Right? Right???

I kinda expect an 8 lb to be too light, because I think that may be what I already tried. If a 9 lb spring is too light, I think I will try to shim it to find something between too light and stock. Anyone know where I could source a 10 or 11 lb MS?

In any case, I am retired and I like a challenge...

 

[Ken6PPC]

I promised to update this thread with what I learned. I got some Wolff reduced power springs, and started to experiment with them. (Stock Numbers 32355 and 16670) The heaviest hammer spring in the kit was 9 lb., and it resulted in ~ 3 light strikes per cylinder full of 7. That happened with both CCI and Federal ammo. The original main spring (12 lb. - I THINK!) was 100%.

I thought of clipping a coil or two from the original MS, but since I didn't have another 12 lb. MS, that would be a one-way trip. So, I made a new Mainspring Rod Swivel (I always called that part a MS cup) Smith And Wesson J-Frame Mainspring Rod Swivels from brass, attempting to duplicate the dimensions of the original the best I could. However, I drilled the seat for the spring about 75 thousandths deeper than on the original, so the spring would not be compressed quite as with much as the original MS cup. It helped - a little.

I tried a few rebound springs as well, and settled on the 13 lb. The lighter ones didn't return the trigger quickly enough for me. Keep in mind that I smoothed the sliding surfaces pretty well before starting on this, and had I NOT done that, I doubt the 13 lb. rebound spring would work as well.

My work definitely made a difference! I can't say exactly how much I actually reduced the trigger pull, because I couldn't even weigh the trigger when I got it!

However, it is now at 10-1/2 lbs., and it is nice and smooth. It is functioning 100%, and I'm happy with it!

I plan to shoot a few hundred more rounds, and if I do have any misfires, I will simply swap out the MS cup I made for the original. It would be nice to find some 10 and 11 lb. MS to try though...

 

[Protocall_Design]

Maybe you could make a taller MS cup for the 9 lb. spring to compress it more. If it didn't work, trade parts back to where you are now.

 

[Ken6PPC]

Maybe you could make a taller MS cup for the 9 lb. spring to compress it more. If it didn't work, trade parts back to where you are now.

When I first thought to make the MS cup, I was planning to do just that - compress the 9 lb. spring more.

However, I was concerned about compressing it to the point of binding, and I used a 5.56 case for material to make the custom cup. The 5.56 case web wasn't thick enough to compress the spring more anyway, if I wanted to use a counter bored hole to hold the spring in its proper position. I thought I should do that.

I might get bored and try making another one, but I would most likely have to use round stock or a Magnum case. It would be a little more difficult. I don't have a picture hosting web site right now, or I would post a picture of it.

 

[NCBeagle]

My experience

Model 351c, Needed Spring Swap Back to Original

 

[Ken6PPC]

My experience

Model 351c, Needed Spring Swap Back to Original

That pretty much is what I found. The next lighter MS that I could find (9 lb according to Wolff) was TOO LIGHT, and I had to put the original MS back in to make it reliable again.

However, I was able to lessen the original MS's force slightly with a custom MS cup (no guess how much difference it made on weight), and still maintain reliable ignition. At least, so far. I haven't shot enough rounds like this to be comfortable with it - YET!

It certainly helped the trigger pull!

 

[BEEBEE]

I like the way you are thinking.

I shortened my spring very little on an LCR 22lr so that I got an 11.5 trigger pull. It was 14.5 lbs. IT matched my model 63 22lr trigger pull at 11.5 pounds. Hundreds of rounds and different ammo in each and no issues.

The current s&w web site for the 351c spec shows a 10lb trigger??
NRA article showed a 15lb spec??

So, I was thinking I would do the same with the 351c until it became unreliable and then shim it to reliability if I could not get another OEM spring. Or find a spring supplier. Out of the box the 351c trigger pull on mine is 13 1/4 lbs. I can live with this, but my shooting sessions may not last as long??
The lightest I have seen on a review by GunBlast was I think 9.5 pounds. Seems too light. Another known YouTube reviewer had a pull just under 12 and another reviewer's was at just over 13 pounds on a 351c and just under 15 on a 351PD.
I think you are doing great at 10.5 pounds. The 22 magnum spec on case wall thickness is .012 to .014. The 22lr is .010 to .012. So is takes a good wack for the 22 magnum.
Thanks for all the info. I have an email in to S&W to see if they will sell me some main sprigs to play with.

 

[BEEBEE]

I promised to update this thread with what I learned. I got some Wolff reduced power springs, and started to experiment with them. (Stock Numbers 32355 and 16670) The heaviest hammer spring in the kit was 9 lb., and it resulted in ~ 3 light strikes per cylinder full of 7. That happened with both CCI and Federal ammo. The original main spring (12 lb. - I THINK!) was 100%.

I thought of clipping a coil or two from the original MS, but since I didn't have another 12 lb. MS, that would be a one-way trip. So, I made a new Mainspring Rod Swivel (I always called that part a MS cup) Smith And Wesson J-Frame Mainspring Rod Swivels from brass, attempting to duplicate the dimensions of the original the best I could. However, I drilled the seat for the spring about 75 thousandths deeper than on the original, so the spring would not be compressed quite as with much as the original MS cup. It helped - a little.

I tried a few rebound springs as well, and settled on the 13 lb. The lighter ones didn't return the trigger quickly enough for me. Keep in mind that I smoothed the sliding surfaces pretty well before starting on this, and had I NOT done that, I doubt the 13 lb. rebound spring would work as well.

My work definitely made a difference! I can't say exactly how much I actually reduced the trigger pull, because I couldn't even weigh the trigger when I got it!

However, it is now at 10-1/2 lbs., and it is nice and smooth. It is functioning 100%, and I'm happy with it!

I plan to shoot a few hundred more rounds, and if I do have any misfires, I will simply swap out the MS cup I made for the original. It would be nice to find some 10 and 11 lb. MS to try though...

75 thousandths longer spring will only reduce preload by less than 14.5 ozs on a 12 pound spring. Right? Polishing and trigger return spring to 13 lbs. must of got you to 10.5 lbs. That's impressive. Wolf springs indicates the factory rebound spring is 18 lbs.