SA Trigger Way Too Light on 629?

I just picked up a used 629 pre-lock, pre-MIM gun.
The SA trigger pull is dangerously light. I'd estimate very easily under 2 pounds (don't have a scale).
The kicker is, the DA pull is a tad on the heavy side.

Strain screw is all the way in, unmodified. Don't know if any springs have been changed, or any smithing done. The mainspring is a dark color, with a pronounced rib running down the length of the spring.

I read many pages of threads about mainspring or rebound spring affecting predominately one pull or the other. Some guys said mainspring mainly affects SA, some said DA. Same with the rebound spring....confusing.

I plan on using this gun in bear country here in MT, so reliability is number one, followed by smoothing the DA trigger.

Any advice much appreciated.

There are two common ways to lighten a SA trigger.

One is to install a lighter rebound spring. Put a 12 lbs. rebound spring in an K, L, or N frame with a factory mainspring and the SA break will drop to a bit under 2 lbs. At the same time the DA trigger pull will run between about 7.5-8 lbs. Some would consider an 8 lbs. DA trigger "heavy" to others it will seem a bit light. One tipoff to a lightened rebound spring is that the pressure of the trigger on the rebound stroke will be noticeably lighter than a gun with a standard rebound spring. In addition with a 12 lbs. rebound spring I've had the action "tie up" during live fire when it's used with the factory mainspring.

The second way to lighten the SA trigger is something that I don't endorse. That is by changing the angle of the SA sear surface on the trigger. Doing this can result in a push off issue unless it's done by an expert with a very good "attention to detail" record.

If you have a S&W that is all factory, compare the trigger return pressure to that of the 629. If it feels light, odds are that a simple change of the rebound spring will solve your issue. If you install a 14 lbs. rebound spring it will result in a SA break just over 3 lbs. Go to the factory 16 lbs. rebound spring and the SA break will be about 4 lbs. Note, as you increase the strength of the rebound spring, the DA pull weight will increase at the same time. Basically, a 14 lbs rebound spring will take the DA pull to about 8.5 lbs and the 16 lbs. spring will take the DA pull to about 10 lbs when combined with the factory mainspring.

BTW, it's been my experience that the absolutely smoothest DA triggers are those in the MIM guns. The earlier Smiths that I have that have forged internals all have a slight "hitch" at the end of the DA stroke that makes it easy to stage the trigger in double action. On my MIM guns the DA trigger is butter smooth from start to finish without any "hitches". In addition, the later MIM guns incorporate features that used to have to be added during an action tuning. If you want a trigger that is truely "bragworthy" you should change your attitude about MIM. IMO, S&W took the time to get everything right when they went to MIM internals and the result is the slickest S&W's I've had experience with are all late model MIM guns.

2 ponds for a single action pull sounds about right.

I believe the stock SA pull is more in the 4# ballpark. A lighter rebound spring definitely lightens the SA pull, a stronger one will make it go up. It could also be somebody stoned the SA sear which means the hammer/trigger might need replacing.

The ribbed main spring is not factory, it is, likely, a Wolff reduced power main spring. That tells me somebody has been inside the gun and modified it. It is very likely that a reduced power rebound spring was also installed. If the sear has not been modified, installing a higher weight rebound spring will, probably, increase the SA trigger pull. It will also increase the DA trigger pull. It seems strange that you have a too light SA trigger and a too heavy DA trigger, though. Usually, the Wolff ribbed main springs result in very smooth DA triggers with noticeably lower pull weights than factory. I suspect that, in addition to the springs, somebody may have performed a "homemade" action job on the gun, modifying the sear engagement (and, perhaps, other internals) without really knowing what they were doing, or simply lacking the necessary skills. Given the current conditions described, I strongly suggest you check the gun for push-off. Cock the unloaded gun, then, without pulling the trigger, push forward on the hammer. It should not fall without pulling the trigger. If it does fall, it is a very unsafe condition, and indicates problems with the sear engagement. That can be corrected, but I recommend either taking it to a good gunsmith or sending it to S&W for repair. Good luck!

I bought two used Smiths which had the Wolff reduced power mainsprings with the rib in the center - a 29-2 and a 624. I replaced the spring in the M29 with a factory mainspring, which significantly increased the DA pull, but had little effect on the SA pull.

I left the Wolff mainspring in the M624 and had frequent FTFs in both DA and SA modes due to light primer strikes. I switched to the "softer" Federal primers and the FTF problem went away.

If you're gun doesn't reliably fire whatever ammo you plan to use, you might want to go back to factory springs.

I did some more digging and found out the gun has had an action job (gunsmith), Wolff factory-power mainspring and reduced power 14# rebound spring.

There is NO push off, even when applying significant pressure.

I plan on replacing the rebound spring with either a 15 or 16# and see if that improves things.

Never thought I'd want to make a trigger heavier!

Your SA trigger pull may be more than you think. I have a 38/44 Outdoorsman that has a hair trigger on SA. I do not have a trigger pull gage so I used a kitchen scale (good quality) and lead ingots to get the weight. I then suspended the weights from a string passing over the trigger (not tied to it). I found that the "hair" trigger broke at 2 lbs. I had expected the pull to be much lighter. With a 2 lb trigger my finger never touches it till I am on target.

I have a model 60-7 (my carry piece) with the original factory springs, and the gun has not had any work what so ever done to it. The double action trigger pull is typical "J-Frame heavy" but better, lighter & smoother than most J's, and the single action trigger pull is crisp 2 pounds. Other than shooting, cleaning & LIGHTLY lubricating this weapon, it's just one that is better than most by sheer luck.

I have an example of almost every S&W produced, and I believe that my M60 has the best single action trigger pull (out of the box) of any revolver I own. Just kind of the luck of the draw I suppose.

chief38