So my latest Perf Ctr 627 has had four (4) failure to fires out of 300 rounds from light primer strikes. One FTF was with American Eagle and I thought it was from being old ammo, then I had three more FTF's from Remington Golden Saber .357 Magnum

Used to I would of dropped the grips and backed out the screw that is pressing in to the spring right? Now I'm reading not to do it, that screw is supposed to be fully seated, and spring adjustments should come from the installation of slightly shorter ones if you need more hammer force.

Problem is, I don't know if the issue is head space or spring adjustment or what.

What is my next step please?

Thank you

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I'm not familiar with the 627 but if you're referring to the strain screw, you tighten it to increase the hammer force, not loosen it. A loose strain screw can cause light hits on the primer.

Yes, leave the strain screw alone. How old is the gun? You may need to adjust the head spacing.

Adjusting the strain screw will lighten your trigger pull. You definitely don't want that if you are already getting ftfs.

Loosening that screw is not the proper method to tune a trigger. It's important to maintain the proper arc of the leaf spring. You can buy lighter leaf springs, that will lighten the trigger pull, to some degree, while maintaining a more reliable primer strike. You can also install a lighter trigger rebound spring as well, but not too light, or you will not be able to maintain a fast double action. Proper stoning various internal parts can aid in creating a smoother trigger pull. But you need to know what you're doing, or you can mess up your trigger/hammer, and possibly create an unsafe trigger!

I just got this gun. It is my fourth 627 not counting a 327, and I've never had this issue.

Thanks.

If this guy doesn't know, nobody does.

I backed out that screw just a turn to lighten the trigger on my 627-5 pro 357. It has not miss fired yet and the trigger pull is lighter now especially in DA.
I figure if it starts having light strikes then I will tighten the screw again. Hasn't happened yet.

Back in the late 60's, a gunsmith taught me something I don't hear about much these days. They used to very carefully narrow the hammer spring, by slowly, and evenly, taking off a slight bit of material off the sides. This method would reduce the spring tension, while maintaining the proper arc of the spring.

That's fine at the range.

Going back to S&W today.

That was sometimes done back in the days before there were lighter spring kits easily available.

Grinding on a leaf spring is not a good idea.
That leaves scratches on the spring that may be so fine you can't see them but they set up stress risers in the steel that will cause the spring to snap.
Not something you want on a defense gun.

Way back when people ground springs because that was one way to get a lighter pull and there were no replacements in lighter weights.

Of course, these days we understand that a lighter trigger is not necessarily a good thing.
What you want is a smooth trigger pull, which will seem lighter.
The lighter the trigger, the higher the risk of mis-fires, and the slower the action reset, which actually slows down how fast you can shoot.
Also, a lighter trigger may cause "short stroking" problems. With a slow resetting trigger you may be attempting to pull it again before it resets and you get a short stroke failure.

MANY times people post on gun forums about reset issues or mis-fire problems and they find the tension screw has backed out under vibration of shooting.
A loose tension screw has nothing to stop it from loosening, which is why they should be tightened down tightly as the factory intends.

Check to see if that strain screw is tightened all the way. My 627pc came from the factory with it backed out 1/2 turn. If it is in all the way, try backing it out till you can see daylight between the screw and the spring . Then add a "shim" between them before tightening the screw down again. A thin piece of matchbook cover, spent primer etc works fine. Just something 30 thousandths or so. No more. Now try the gun again and see if it's cured. If it is, you can get a longer strain screw ( or a better shim) to fix it for good. If it isn't, your problem does not lie with the screw length.

__________________
Dave

At the end of this video Jerry addresses the strain screw and how to adjust it. Contrary to what we all hear in posts about it can't be loosened, I'll take Jerry's word that it can. This guy IS Mr S&W

He's good, but I'll go with what the S&W factory says.
They invented the gun and know more than anyone.
They say the screw should be tightened down and kept tight.

In the end it's your gun and you can do what you want.
If it works for you, great. If it fails at a bad moment, you punched your own ticket.

If a strain screw is backed out it is not tight and will move under recoil. The only way the screw should be is tightened down. Now, you can shorten the screw and accomplish what loosening it up had done, but keep the screw tight so it doesn't walk back out. Just order a couple of extra screws before you begin filing one down.

__________________
H Richard
SWCA1967 SWHF244

I use factory hammer spring and reduced power trigger return spring after making sure everything is burr free and smooth. I prime empty cases and use them as I back out the screw till I get misfits, then tighten up 1/2 turn and fire 24 primers without a failure. Then tighten again counting the turns. For example let's say it takes 2 1/2 turns to get it real tight. Remove screw and measure overall length. It is a 32 to the inch screw. Each turn moves it .03125, x2.5 is .078125. File about .070 off the end of screw leaving tip slightly rounded and try that. A little long is better than short.

I learned long ago a loose screw will back out and it WILL happen at a bad time. For me it was during a a bowling pink match.

The problem with backing off on the strain screw is that once you loosen it, it may continue to loosen on its own until suddenly, the gun won't fire.

At the S&W Academy, if a revolver's double action trigger pull exceeded 12 pounds, we'd shorten the screw in slight increments until the 12 pound threshold was reached.

I have the same revolver and the same problem. I double checked the screw and also got an aftermarket firing pin and spring. It is simple to change it out. Haven't had a problem since. The new spring was just a hair longer.

don't forget to check the endshake . that was the prob with my ftf

When I went to the factory armorers school, one of the instructors said the mainspring screw was on of the biggest mistakes made in engineering... because if it is not kept tight, it will back out. The instructor's solution was to lightly file down the tip of the screw to achieve the desired effect but not too much or light indent on primers will be the result. Then a new screw is required. Jerry may fool around with his revolvers but I carry to protect against targets that may fire back.

If you do decide to lighten the strain screw a little purple Loctite will keep it in it's place. It will also allow you to adjust the strain screw back down if needed.

This is good for a competition gun but never for a carry gun. Make sure you are getting 100 percent ignition no matter what you do.

I would not have imagined so many people on this forum espousing loosening the strain screw to tune a trigger pull. That is such an amateur's play it is beyond ridiculous. If Jerry Miculek is doing it, he is wrong. If he is promoting doing it to people that don't know any better, he is doubly wrong. He is not God, not even of Smith and Wesson.

Jerry Miculek's requirements are totally different from most. He's a trick-shooter, and entertainer. I'm sure if you asked him, his defense revolvers are not adjusted in the same manner. He should make that clear, in the beginning of his videos.

To finally answer the OP question directly, the answer is yes, you can. I did it to numerous Smiths back before the trick springs were available. Didn't cause me any problems that I remember. That said, in today's information rich environment there are better, more dependable methods which I would encourage you to use. Much good advise posted above on the better mousetraps.

I know it is not according to the Smith & Wesson Bible, but I use the strain screw back out method . I use a trigger pull gauge to measure the pounds required to release the trigger. I also use Loctite on the threads and nail polish on the screw head to hold the screw in place once it is adjusted to the correct tension. That allows a very good visual indication of whether the screw has moved or not. With nail polish on the screw head the screw will not back out.
I have used this method for 15+ years and have never had a strain screw move under fire. I also use the old school method of shaving the hammer spring not narrowing it. I feel I get better results or at least equal to using a Wolf reduced power spring. I've used this method with many Smith & Wesson revolvers and have never had a leafspring failure. I know this is old school but I'm old-school also.
I don't try to get extreme light trigger pulls, I usually have my trigger pulls on larger frame weapons such as N and L frames around 8 1/2 pounds . It does require federal primers fully seated. Using Federal primers I do not get light strikes . Again I agree this is not for a save your life defensive carry weapon this is for fun and competition only.
Im sure this will go against what most people believe but it has worked for me for a very long time.

Where many people get fouled is in not understanding the difference between a life and death defense gun and a range toy.

If a range toy fails, nothing bad happens.
If a defense gun fails....you die, and guns are unreliable enough as is.

So, if it's a range toy...have at it.
If it's a real defense gun you punch your own ticket.

This applies to no one but me. I have had a good deal of experience with PC guns. I have come to believe the PC folks fool around with these things and have them as light as possible when screwed all the way in. SO, when you back out on them, even a little, bad things start happening. We pay more for PC guns then start monkey muckin with them till we have problems. As Waltrip once said about Earnhardt, "He's gonna fix that thing til it's broke".

In the days when S&W built revolvers with the hammer nose (firing pin) on the hammer, you just did not hear of light strikes like we do now with the frame mounted firing pin. There are those who say that is because we have the internet and forums where we all see in one place the few rare cases. I am not buying that, based upon almost 50 years of shooting S&W revolvers.

So, what I was taught in the dark ages is that the strain screw must be full length and screwed right down. In other words, do NOT back it out at all. Ever. For any reason.

The screw is designed with a shoulder such that if it is screwed right down, it will not back out, and it does not require loc-tite or any nonsense.

These days, when everyone believes the secret to great shooting is not practice, but a light pull, I have no idea what to tell people. I learned to shoot double action when a great DA pull was 12 or more pounds, but smooth.

Now, people think a six pound pull on a Glock, or a 7.5 pound pull on an M&P auto loader is horrible requiring loony parts to correct the "problem."

My advice is to return it to factory springs and strain screw for a standard revolver (not a PC version) and see what happens. If you still get light strikes, you have a headspace problem. In that case, send it to S&W.

Naturally, I would say send it to S&W now, provided you have not modified the trigger pull in any way (springs or strain screw). If you have modified springs or strain screw, assume the whole affair is your fault, send it S&W for correction, and then when you get it back, don't do it again.

If you have not modified it, then it is S&W's fault, and you should send it back for a good going-over.

Good luck.

I have watched that video, and Jerry does NOT say it is ok to just back out the screw and leave it there.

What he describes is going to the range with your ammunition, backing it out until it is as light as it can be with your ammo and still have 100% reliability, then going to the bench and measuring with a caliper the difference between how much the screw sticks out in its loosened position versus when it is tightened all the way down to its locked position.

He then says to remove the screw, clamp it in a vice and to file down the end of the screw so that when it is tightened all the way down to its "lock position" it is putting the same stress on the mainspring as in the loosened position prior to shortening the screw. This way you get the light pull without the possibility of the screw backing out further.

So, before everyone piles on Mr. Miculek, watch the video. You will find that he does NOT recommend simply running with a loosened screw. His discussion of the issue begins at about 4:27.

My first gun was a Daisy, it had, most likely a lousy trigger. I learned to shoot that thing very well because I shot it a lot. I have never felt a need to customize an action or trigger.

99% of the S&Ws brought to fix, had broken mains and backed
out tension screws. If the main doesn't take the "load" the way
it's designed, it will snap off at the top. I've had a couple that the
tension screw was stripped from idiots thinking the tighter it is in
the lighter the trigger pull. Also have had several cases of Buuba
putting the spring to grinding wheel. I have seen aftermarket
mains that struck so light they would not put off CCI primers in
357. When you have light strikes, it can cause ununiform ignition.
If you are bullseye shooting this can open up your groups. To many people watch old westerns, were every night the cowboy
takes his Peacemaker apart and tunes it with a file about a foot
long.

I received a 627PC that had 7% failure to fire due to light primer strikes. I called S&W and they sent me a shipping label - sent the gun off. It returned with a new firing pin, new cylinder and new crane. That would not have been a repair that I would have been willing to undertake at home, but I don't think that they would have performed those operations had they not been necessary to repair the underlying problems that lead to the light primer strikes.

S&W has a lifetime warranty on these guns and they charge enough for the gun that it should either work properly or be repaired. My advice would be to call customer service and explain what you are experiencing with this gun and see if they advise a return to the factory.