New 625-8 JM light primer strikes with Wolf kit

[linko]

Well I purchased a new JM and installed the wolf spring kit. I used the medium rebound 14lb spring. First trip out with a pile of Blaser Brass 20gr FMJ ammo. Well that was a disapointment. 40% light primer FTF's. I have the main spring adjustment screw all the way in. Geeze. I wanted a nice trigger feel but it would be also nice if the gun fired.

So background. Hard to believe for you all, but this is my first revolver.

I read a fair amount of posts about this gun having light strikes. Is the recommendation to forget Wolf and return the gun to factory spring for my next trip to the range? I changed the Wolf rebound from the medium 14 to the 15lb and was going to try that next trip.

 

[scooter123]

Leave the 14 lbs. rebound spring in place, that has NOTHING to do with the power generated by the mainspring. It also has almost zero effect on the trigger pull in Double Action but does reduce the Single Action trigger pull from 4 lbs. to a bit over 3 lbs. What you need to do is put the factory mainspring back in place, that is directly linked to the power generated by the hammer strike.

Now, for properly tuning the 625 JM. You really need a trigger pull gage of some type, going by "feel" just doesn't cut it. I prefer the Lyman Digital trigger gage but that is a 65 dollar purchase and I can understand why you wouldn't want to spend that much. Look around at Midway or Brownells and you should find a basic spring scale gage in the 20-30 dollar price range. If you shop at Brownells I would recommend purchasing some spare Strain Screws because you will need them. BTW, I prefer the black steel screws because I've found that the stainless steel strain screws are softer and will peen shorter at the tip in only 1500 rounds fired. Once the tip of the strain screw peens over enough to reduce the trigger weight it becomes a distinct hassle to remove because you have to remove the mainspring and file the resulting burr down using a tiny needle file with the screw in place.

One item I recommend you install is a Cylinder & Slide Extended Length Firing Pin. This will increase the firing pin effective length by about 0.015 inch and allow reliable ignition with a lightened trigger with or without the use of moon clips. However it should NOT be used with the original factory trigger pull of about 12.5 lbs., you really need to tune the trigger to 9.5 lbs. or less to install this firing pin. Because with the original factory trigger weight there is a distinct risk of a pierced primer.

Tuning. Install a 14 rebound spring and then shorten the Strain Screw enough to reduce the Double Action trigger pull to 9.0 lbs. using the original factory mainspring. Filing the tip of the Strain Screw so that the overall length is shorter by about 0.020-0.025 inch should get you into the 9.5 to 10 lbs. ball park. Once at that point you then need to work it down to 9.0 lbs. in increments of just 0.002 inch. Yeah, it really is that sensitive and you'll now understand why I recommend having some spares on hand. You'll also understand why I prefer the black hardened screws over the stainless version.

Note, you can go lighter than 8 lbs. but that will require taking steps to minimize any drag on the hammer that might reduce the power of the hammer strike. I would suggest shooting at least 1500 rounds through the revolver before attempting this because any areas causing drag on the hammer will show up as rub marks in the frame recess or sideplate. You can then make up some tiny shims to re-position the hammer using 0.001 or 0.002 inch thick shim stock. BTW, the easiest way to put a hole in shim stock this thin is with a diamond burr in a Dremel. Second easiest is using a drill with the shim clamped very firmly between 2 pieces of hard maple or oak. Once the hole is drilled you can then trim the shim using basic paper cutting scissors. Note, total shim thickness should NOT exceed 0.003 inch because putting in to much shim will start causing the hammer to bind when the sideplate is tightened down.

 

[robert1804]

Thanks for this timely post. I tried a Wolf main spring in a new 67 and had light strikes. I also used the 14# return spring. I'll try filing the set screw since I'm ordering some stuff from Brownell's anyway.

 

[linko]

Leave the 14 lbs. rebound spring in place, that has NOTHING to do with the power generated by the mainspring. It also has almost zero effect on the trigger pull in Double Action but does reduce the Single Action trigger pull from 4 lbs. to a bit over 3 lbs. What you need to do is put the factory mainspring back in place, that is directly linked to the power generated by the hammer strike.

Now, for properly tuning the 625 JM. You really need a trigger pull gage of some type, going by "feel" just doesn't cut it. I prefer the Lyman Digital trigger gage but that is a 65 dollar purchase and I can understand why you wouldn't want to spend that much. Look around at Midway or Brownells and you should find a basic spring scale gage in the 20-30 dollar price range. If you shop at Brownells I would recommend purchasing some spare Strain Screws because you will need them. BTW, I prefer the black steel screws because I've found that the stainless steel strain screws are softer and will peen shorter at the tip in only 1500 rounds fired. Once the tip of the strain screw peens over enough to reduce the trigger weight it becomes a distinct hassle to remove because you have to remove the mainspring and file the resulting burr down using a tiny needle file with the screw in place.

One item I recommend you install is a Cylinder & Slide Extended Length Firing Pin. This will increase the firing pin effective length by about 0.015 inch and allow reliable ignition with a lightened trigger with or without the use of moon clips. However it should NOT be used with the original factory trigger pull of about 12.5 lbs., you really need to tune the trigger to 9.5 lbs. or less to install this firing pin. Because with the original factory trigger weight there is a distinct risk of a pierced primer.

Tuning. Install a 14 rebound spring and then shorten the Strain Screw enough to reduce the Double Action trigger pull to 9.0 lbs. using the original factory mainspring. Filing the tip of the Strain Screw so that the overall length is shorter by about 0.020-0.025 inch should get you into the 9.5 to 10 lbs. ball park. Once at that point you then need to work it down to 9.0 lbs. in increments of just 0.002 inch. Yeah, it really is that sensitive and you'll now understand why I recommend having some spares on hand. You'll also understand why I prefer the black hardened screws over the stainless version.

Note, you can go lighter than 8 lbs. but that will require taking steps to minimize any drag on the hammer that might reduce the power of the hammer strike. I would suggest shooting at least 1500 rounds through the revolver before attempting this because any areas causing drag on the hammer will show up as rub marks in the frame recess or sideplate. You can then make up some tiny shims to re-position the hammer using 0.001 or 0.002 inch thick shim stock. BTW, the easiest way to put a hole in shim stock this thin is with a diamond burr in a Dremel. Second easiest is using a drill with the shim clamped very firmly between 2 pieces of hard maple or oak. Once the hole is drilled you can then trim the shim using basic paper cutting scissors. Note, total shim thickness should NOT exceed 0.003 inch because putting in to much shim will start causing the hammer to bind when the sideplate is tightened down.

Thank you very much to take the time explaining the process. I will ask one further question. Is there any issue using the Blazer Brass brand of ammo?

 

[OKFC05]

If you lighten the mainspring enough, you get into having to use Federal primers for 100% ignition. I have done that in my IDPA revolver (7#), but keep the trigger closer to 10# in my other revolvers so they will shoot ammo like Blazer. I have to use factory ammo for students.

 

[scooter123]

There is absolutely nothing wrong with Blazer Brass ammunition unless you use the cases to reload. In that case you'll need to use a pocket swager on every case because Speer and Blazer cases feature crimped primers using a crimp method that is distinctly subtle.

I can also tell you that I've been using CCI primers, which are what is used in Blazer ammo, and they are not nearly as "hard" as the internet claims they are. In fact the "hardest" primers I've encountered recently are Remington and it's because of Remington UMC in 45 ACP that I retuned the trigger on my 625 JM from 8 lbs to 9 lbs. BTW, I really really like Remington cases in 45 ACP for reloading, no fussing with crimped primer pockets and the cases are always Large Pistol.

 

[9mmsubgun-m11]

I have had my 625 JM for about 4 months now and have done a couple things that have the trigger pull to my liking. First was a stoning of the internals-Did Not Touch Any Sear Surface. Installed Wolff 15lb rebound spring. Backed out the strain screw 1/2 turn and used a little blue Loctite. 100% positive ignition using my own loads with Winchester primers. Able to shoot 1" groups double action at 25'. As always YMMV.

 

[forrestinmathews]

Hi,
I don't know too much about tuning revolvers, but what I do know works.

Your wolff mainspring has a rib in it. This effectively decreases the strain on the mainspring. That is why you are getting light strikes. Unless you can make the mainspring magically longer...you're done with the stock strain screw.

Take 2000grit sandpaper and shine up the trigger rebound shuttle. Shine up all the surfaces it rides against except the trigger and hammer. Replace the 14# rebound spring. It is good enough that you won't out run it shooting fast and it will keep the pull lighter. Don't go bananas and change the geometry of anything, you're just making it smoother.

Skip the Cylinder and Slide extended firing pin. It's junk and will break in about 20,000 dryfires shearing about two milimeters up from the base of the pin. Apex Tactical Specialties extended firing pin. The XP model NOT THE COMPETITION MODEL for .45's. These are bullet proof. I've had mine for about six years and I dryfire a lot.

Skip the strain screw. You can fool with that all night long and try to get it right. Take too much off and you are right back to clickville. Locate a stainless steel 8-32x 3/8" set screw. Apply BLUE LOCTITE and screw down until the distance of the spring from the frame along the center of the screw measures 0.110-0.115". At this point you should have enough hammer force to reliably set off Federal Primers. If you want to use others increase to 0.125-0.130. THE ADVANTAGE TO THIS METHOD IS you can take the Allen wrench TO THE RANGE and ADJUST THE STRAIN to the MINIMUM NECESSARY FOR RELIABILITY. When adjusting I go in quarter turns at the range and then measure when I get home. Blue loctite is key as it is releasable and will hold your setting in place until you change it.

You CAN tell if a hammer setup is heavy enough by feel. With the cylinder open, hold the cylinder latch rearward. Place the tip of your finger over the firing pin hole pressing down with sufficient force to smooth the stamp on a letter. Squeeze the trigger. If it burns you're good.

Scooter 123 knows his stuff for sure, but my way is slightly different and I stand by the Apex pins over C&S.

Best of luck. Feel free to PM with any questions.

 

[H Richard]

Before you file anything, put the original mainspring back in and take the gun out and shoot at least 500 rounds through it. If it is still unsatisfactory, then try something else. I've got over 75 S&W revolvers of all sizes, and have never needed an extended firing pin or an aftermarket mainspring.

 

[jtcarm]

It would be much easier to simply buy your shims here, if it's determined you need them:
http://triggershims.com/sw_k_l_n_frame.html

But Forrest is right, the best thing you can do is smoothing. 2000 grit wet or dry from the auto parts store is handy & cheap stuff that'll get steel surfaces super smooth. I keep an assortment of 600 - 2500 on hand.

I also suggest this video so you know where to tune. He does all the work with a medium stone, but after stoning you can polish things up really well with the sandpaper. The gun in the video is forged parts but there's very little difference.

http://www.midwayusa.com/product/26...-for-s-and-w-revolvers-with-jerry-miculek-dvd

 

[Blackshirt]

I always use an Apex XP Firing Pin Kit when I use reduced power mainsprings. It uses the slightly longer firing pin and a reduced power fp spring...16 bucks:
https://store.apextactical.com/WebDirect/Products/Details/192059

 

[andyo5]

Jerry Miculek (the guy who the "JM" is named for) has a video on his website about tuning the action on a S&W revolver. It involves reducing the length of the strain screw. Your 14lb rebound spring is correct. Leave it alone.

 

[ghstrydr164]

Leave the factory main spring in and fully tighten the strain screw, leave the #14 reduced trigger rebound spring which has everything to do with double action pull weight and some reduction of single action pull weight, but nothing to do with primer detonation.

Very slow deliberate double action firing can cause problems with primer detonation because the hammer trips earlier on slow double action (when the mainspring is not as fully compressed). the Inertia created by fast double action pull gives the hammer more travel and creates more compression on the main spring more like single action compression.

Best test methods are take your gun out and using the same ammo shoot a cylinder full on single action first. If all rounds fire then fire a cylinder full on fast double action. If all rounds fire then fire a cylinder full at very slow deliberate double action.

If all rounds fire then you are good to go. If some do not fire on single action or fast double action then you need a heavier main spring, if they fire on the single and fast double action but not the slow, deliberate action then you must decide if you want to leave it like that or replace the mainspring with a heavier one.

I hope I have explained this in a clear and understandable way.

 

[jtcarm]

Leave the factory main spring in and fully tighten the strain screw, leave the #14 reduced trigger rebound spring which has everything to do with double action pull weight and some reduction of single action pull weight, but nothing to do with primer detonation.



Very slow deliberate double action firing can cause problems with primer detonation because the hammer trips earlier on slow double action (when the mainspring is not as fully compressed). the Inertia created by fast double action pull gives the hammer more travel and creates more compression on the main spring more like single action compression.



Best test methods are take your gun out and using the same ammo shoot a cylinder full on single action first. If all rounds fire then fire a cylinder full on fast double action. If all rounds fire then fire a cylinder full at very slow deliberate double action.



If all rounds fire then you are good to go. If some do not fire on single action or fast double action then you need a heavier main spring, if they fire on the single and fast double action but not the slow, deliberate action then you must decide if you want to leave it like that or replace the mainspring with a heavier one.



I hope I have explained this in a clear and understandable way.

Well this has become a thread of differing opinions:

I've reduced DA pulls substantially by filing or grinding the main spring. I clipped a coil off of a stock rebound spring once and the only perceptible difference was a more sluggish trigger return.

BTW I've never ruined a main spring. The only time one of my guns has failed to pop a primer was when the strain screw was loose. I always leave the screw complete tightened.

 

[ghstrydr164]

Well this has become a thread of differing opinions:

I've reduced DA pulls substantially by filing or grinding the main spring. I clipped a coil off of a stock rebound spring once and the only perceptible difference was a more sluggish trigger return.

BTW I've never ruined a main spring. The only time one of my guns has failed to pop a primer was when the strain screw was loose. I always leave the screw complete tightened.

Shortening a spring is not the way to go so I am not surprised at the outcome of your rebound spring experience.

In order to double action cycle the S&W revolver the trigger must compress the rebound spring. The function of that spring is to return the trigger to its original position. S&W puts a heavier then necessary rebound spring in their revolvers for liability reasons.

A Thirteen or Fourteen # reduced power rebound spring will improve the double action and single pull much more then any main spring lightening and still return the trigger reliably under any type of double action use. Even if you remove the main spring you will still have a very heavy double action pull because the trigger must still compress the rebound spring.

My opinion is shared by most if not all top competition shooters including JM and most S&W revolver smiths along with many other procedures that help produce a much smoother, lighter and reliable S&W revolver double action trigger pull but almost none of them if any would suggest filing or grinding the main spring to produce an improved double action and single action pull.

If your way gave any good reliable results it would be being used by the same shooters and smiths referred to above.

 

[Gunhacker]

I too am a recent 625-8 JM owner, I went the Wolf reduced power spring kit route, and noticed right away that with the recess of the rib in the main spring, the strain screw is way too short to properly tension it.

Now here's the interesting part... I've also just become the owner of a 986 Pro Series, which is the 7 shot 9mm on an L-Frame. One of the things touted on it is the "Performance Center" 10lb main spring that lightens and improves the pull.

Being the commensurate tinkerer that I am, opened it up out of curiosity to see what a "Performance Center" main spring looked like... gee, it has a rib and looks suspiciously like a Wolff reduced power main spring, the strain screw was longer and familiar looking. I removed it to discover that it was the longer strain screw for a square butt frame being used in a round butt frame.

Then the light bulb went off... they used that to offset the recess of the power rib. I retrieved a spare square butt strain screw, popped it into the 625-8replacing the round butt strain screw, it works great.

Whenever I use any reduced power springs, I always test the gun afterwards by firing empty cases primed with what I used for reloading, which is CCI, I'm getting nice solid hits.

The way I figure it, if S&W is indeed shipping out 986's from the factory, with a reduced weight ribbed mainspring looking like a twin of a Wolff spring and using a square butt strain screw, and I in turn use the same setup in the 625-8, and it works... how bad can that be?

Oh... and I'm also running with the 14lb rebound spring, in both guns.

 

[Hopper]

I did a fair bit of research myself, and IIRC, the Wolff mainspring has a "rib" in it, no? I went with the Wilson Combat spring kit, and their 13# trigger return spring. This combination has yet to have a light primer strike on a variety of ammo, from Winchester to Federal to Remington. Also, I did NOT install an extended firing pin, which is available from Apex. Which, FWIW, I think I would go with Apex ahead of Wolff. Either way, Wilson or Apex, it's roughly a $20 experiment.

Just my $0.02, as I've read plenty of reports of folks having great success with the Wolff kits too.

*Edit* - sorry, just read the post above more carefully about the ribbed mainspring in the JM 625. I've read where folks seemed to have trouble getting the strain screw to sit properly with the rib, but maybe not the case if they come from S&W that way?

 

[forrestinmathews]

Shortening a spring is not the way to go so I am not surprised at the outcome of your rebound spring experience.

In order to double action cycle the S&W revolver the trigger must compress the rebound spring. The function of that spring is to return the trigger to its original position. S&W puts a heavier then necessary rebound spring in their revolvers for liability reasons.

A Thirteen or Fourteen # reduced power rebound spring will improve the double action and single pull much more then any main spring lightening and still return the trigger reliably under any type of double action use. Even if you remove the main spring you will still have a very heavy double action pull because the trigger must still compress the rebound spring.

My opinion is shared by most if not all top competition shooters including JM and most S&W revolver smiths along with many other procedures that help produce a much smoother, lighter and reliable S&W revolver double action trigger pull but almost none of them if any would suggest filing or grinding the main spring to produce an improved double action and single action pull.

If your way gave any good reliable results it would be being used by the same shooters and smiths referred to above.

Clipping a coil and a half off of the factory rebound spring is an old way of improving the trigger pull without sacrificing positive rebound. Not exactly necessary anymore with the abundance of aftermarket parts, but it still works.

You can add an appropriate diameter ball bearing on the rebound spring also to make up for the loss of spring length gaining a benefit of the spring remaining centered in the rebound shuttle. Another older trick...usually done on purpose and planned, but might work to restore over zealous trimming.

Grinding on mainsprings is also a timed honored tuning method for producing consistent double action pulls for PPC and other revolver sports. Parabolic spring contours and lightened springs can achieve amazing trigger pull results with Federal primers.

I call your hand for lumping yourself in the same sentence with Jerry and other top competition shooters in an attempt to give credibility to your opinion. So unless you have results to back up the talk on the national or even state level kindly blow your smoke greater than 25 feet from the building.

 

[tomcatt51]

There's a pretty good discussion about setting up 625s here:
http://smith-wessonforum.com/s-w-smithing/356297-625pc-hammer-weight-adjusting.html

 

[Blackshirt]

Cutting a spring actually stiffens the spring rate. Think about what happens if you straighten out the wire of a spring. Which will deflect easier; the long wire or the short one? Coil springs must remain their standard length to produce their stated resistance...