625PC Hammer weight Adjusting

[Bearbait in NM]

Finally an update. Sorry it has taken so long, but these things take time, and I like to post results when folks have been so helpful.

I have the gun running with an acceptable setup now. I am running right at 9 lbs DA, and 2.5 SA. The gun started out at close to twelve DA, and 3.5 SA. A couple of things I will start with. The stock mainspring is indeed a Wolff reduced weight spring. per input, it appears the stock rebound spring was 18 lbs.When I first started tweaking and testing, I made a couple of "mistakes". First, I was playing with reduced rebound springs, different firing pin and the gun pretty much stock, all at the same time. Need to isolate variables.

When I first got started, I knew I needed to do some polishing to some parts, verify others for no rubbing (like hammer) and oil and dry fire to break things in. I reinstalled the factory titanium firing pin, polished a bit, and commenced to dry firing like crazy, as well as live fire.

The most obvious and astonishing thing I found was when I tried a 13lb rebound when the gun was very new, the return was awful. Sluggish and bad. After my polishing and a lot of dry and live firing, things have really loosened up inside. I installed a 12lb return spring last week and tested. It is now absolutely reliable with the 12, and the reset is plenty strong. This got my SA to 2.5 lbs. Perfect for me, as the gun will see a lot of SA time.

I have played with loosening the strain screw, and to work with CCI primers and mixed brass of questionable primer seating pressure (old Dillon loads in my stash) I have found that 8.5 lbs DA is right on the edge. No problems with CCI and Starline 45 Super brass, nor Winchester brass and WLP's seated by hand. I bumped it up to 9 lbs to make sure everything will go bang, no matter the primer brand or seating depth. All six chambers will also ignite brass dropped into the chambers, as long as the crimp is no less than 0.469 for mixed brass. I know 9 might sound high to many, for me the difference in the 3 lbs is like night and day DA.

Once I can locate a few extra SS strain screws, I will probably dress them down for a couple of different weights, so that I can seat them fully. Whether dressed shorter for reduced weight or stock, mine needs loctite. It is amazing how little firing it takes to back out my screw, even when snugged up pretty tight. And I think that the stock TI fp does in and of itself not need replacing.

Those of you who said polish, were spot on. Both by hand, and by firing (live and dry). I knew that use would break things in, but I was surprised by how much. This forum has been most helpful. And, the Revolver subforum over on Brian Enos's is most informative. I have no intention of ever going as far as those folks, but they sure have the minutia worked out. I have read through several years worth of posts here and there. My first handgun was a Model 19, 30 years ago. This 625 is really my first DA, since. I am really looking forward to having some fun with it.

Thanks,

Craig

 

[tomcatt51]

And, the Revolver subforum over on Brian Enos's is most informative. I have no intention of ever going as far as those folks, but they sure have the minutia worked out.

Yes, all the little things add up. You should be able to get reliable ignition with hand seated CCI primers with a 7 1/2 lb DA pull, a 12 lb rebound spring and a full (non bobbed/lightened) hammer.

Might get a new S&W firing pin. they're now .495 and still titanium and seem to be optimal. Clip the firing pin spring so it holds the firing pin tip back about .030" (at most) from the recoil shield face when you just drop it in, cross pin not in place. Drop the spring in clipped end first. That's all it needs and you're then robbing as little as possible from the hammer fall. Do reinstall the firing pins' cross pin after shortening the spring.

The PC guns do come with a Wolff reduced power mainspring. There's a S&W part number for them.

The stainless S&W strain screws are horrid things. The alloy/heat treat is just wrong. They forever loosen and the tips deform. An 8-32 socket set screw works much better, doesn't deform, and stays in place better than the stock strain screw. A drop of 290 Loctite will guarantee that but they've also stayed put when I've forgot to loctite them after getting them adjusted. Filing a small notch in the socket end lets you index them for repeatable re-assembly.

Check the sides of the hammer for marks from dragging. The lock assy frequently drags on the hammer (good reason to take it out) and even without the lock assy the hammers frequently drag on their left side requiring a shim on the stud before dropping the hammer in place.

The rebound slide (as I think you found out) is the place you get the most from smoothing. Note I DIDN'T say polishing. Just a flat stone for the bottom and sides. Just taking off the high spots, those surfaces that look pretty good you find aren't after you see the pattern from a few strokes across a stone. 30 - 40% "shiny" and the rest black is plenty. You're really just flattening out the high spots.

The 625-8s benefit from having their chambers reamed. They're undersize and out of round round. You may be ok with brass that's only been fired in your revolver but you can have issues with brass that's been fired in a semi-auto, Glocks being worst. Your re-sizing can leave brass that is still too big (just above the extractor groove) to chamber and the rds don't drop in like they should. Reaming the chambers (SAAMI spec finish reamer) fixes that. Good time to chamfer the chamber mouths while they're being reamed.

The Kuhnhausen book is not very helpfull for this type of trigger work, Jerry Miculeks' "Trigger Job" video is much more usefull.

Have fun. The difference between 9 lbs and 7 1/2 lbs you'll find very noticable. 7 1/2 lb DA, 2 1/2 lb SA isn't a bad way to go.

 

[Bearbait in NM]

Tom,

Thanks for taking the time to follow-up.

I have been scouring the usual places for the S&W firing pin. I guess I need to go direct with S&W. I had not heard about clipping the spring. If I can get spare(s), I'll give that a try.

I already have a pile of 8-32 socket cap screws. I too am trying to find the stock one on line, as I figured it would be easier than dressing the tip on the socket screw to fit the spring rib. Might just go ahead and do that. I also like to be able to check things with my multi-tool screw driver bits, as I always have that on my belt. But I carry other wrenches for my red Dot, so what the hey ;^)

My hammer looked pretty good as I looked at it, but I do have shims coming in. Thought I would try them just to be safe. I did not inspect my lock interface closely, sounds like I need to, or the shims might help. I'm still on the fence about the "Plug" or leaving it stock.

I have a spare rebound slide coming in as well. While I can't imagine ruining the stock one with proper stones, I wanted to have the spare before going above just polishing. But I will do so.

I actually have a cylinder finish reamer. I managed to get one years ago by mistake when trying to get a auto finish reamer. This is the one place I am really torn. I have a ton of old brass, of all types, and everything fits the chambers well. It will also seat perfectly 45 Super rounds with heavy .452 lead bullets with much of the bullet bearing surface above the case mouth, and a bit of swell on the case body from the bullet base. As I noted it will also fire without clips. I am not convinced that my chambers are out of spec. If so not by much. I know from finishing 1911 chambers that there is a fine line between cleaning one up, and not hitting the stop ledge and increasing headspace. I think what I may do here is number my cylinders and get serious on the bench and see if I can see anything on paper. Maybe next time out I will take a just fired clip, and rotate it around the cylinder to see if the fired cases will slide into other holes. Is there a pin gauge or or go no-go that can be used to really check this?

I think I am good to go at 8 1/2 right now, with more recent rounds that have had the CCI primers hand seated. I am not really reloading with my Dillon these days, as I am in a smaller living arrangement. The 9 seems to be needed only with my big pile of mixed brass, loaded on my Dillon years ago. I know back then I was not paying strict attention to the primer stroke, other than making sure none were high.

I bet I can find another pound, somewhere ;^)

Thanks again,

Craig

 

[tomcatt51]

I actually have a cylinder finish reamer. I managed to get one years ago by mistake when trying to get a auto finish reamer. This is the one place I am really torn. I know from finishing 1911 chambers that there is a fine line between cleaning one up, and not hitting the stop ledge and increasing headspace.

I have the Clymer reamer. It's "safe edged" so when it hits the mouth ledge it doesn't cut further. Makes reaming a "no brainer". If the reamer cuts you know you needed to use the reamer. Make sure you use the good brown nasty cutting oil. 625-2 chambers were so bad S&W was warrantying cylinders for undersize chambers. Now they seem to be happy if factory ammo drops in. They don't seem to care if your reloads won't...

I went thru this quite a while ago with brass that wouldn't drop in and started checking chambers with a telescoping gauge and verniered mic. Aside from small, the chambers could be .004" out of round. It's hard to drop a .480 piece of brass into a .479 hole...

As to headspace, drop a new piece of .45 acp brass in the chambers. All of the ones I've checked are cut ~.015" too deep (C&S firing pins are .015" "too long", coincidence?) to actually headspace off the case mouth. Un-reamed chambers with non-moonclipped rds usually headspace off the rds getting "wedged" in the chamber. The rds are meant to headspace off the moonclips in S&W revolvers. Or off the rims with .45AR brass.

The S&W firing pins I've got from both Brownells and Midway lately have been .495. This seems nit picky but the .487ish firing pins S&W was sending the guns out with really were a big deal.

Rebound slide: Use a stone, you're flatteneing high spots not polishing. Look at the cut pattern, you'll see how "not flat" the rebound slides' faces are. If you get to where you're cutting 40% of the surface that's plenty. More is not better.

For strain screws I use socket set screws, not socket head cap screws, no head, great range of adjustment and loctite as necessary. My Herretts' wood grips cover them.

The blued, carbon steel, S&W strain screws are MUCH better than the stainless ones but they're blued and your frame's stainless so there's the color mismatch...

Good luck, There's more but these are the areas where you get the most bang for your buck.

 

[Bearbait in NM]

Tom,

I just dug out my reamer, the one I ordered by mistake from Brownells years ago for a 45 auto pistol. It is a Clymer, but definately not safe sided at the stop ledge. I carefully dropped into each of the chambers, and can feel it stop at the ledge. I did not do any twisting or cutting. As I noted, mine stock accepts every type of brass reload I have been able to check. All rounds drop in freely and hit the stop ledge. I have fired a lot of reloads without clips, and the only issue I have is a few that are crimped a little much will push past the stop with the hammer drop. Anything crimped 0.469 or greater fire just fine. I really think I have mostly proper chambers, stock. Perhaps my cylinder got a fresh reamer before they cut it ;^) And I am clear that the gun is not supposed to headspace un-clipped rounds properly, but mine seems to just fine. All rounds pass the 45acp pistol "plunk" test. If mine will shoot acp properly headspaced off the case mouth, I would rather have that than have to fiddle with AR cases. Not shooting to make this happen, but do not want to wreck this ability if not necessary ;^) I actually like the moon clips, but might be handy to be able to drop in rounds if I want.

I absolutely want to lay my hands on a S&W stock TI fp that hopefully will measure 0.495. My gun is only a few months old from the factory, and came with a 0.490. I initially tested the C&S fp, but I think even though longer, the more blunt tip profile does not work as well as the stock TI pin. The C&S weighs exactly twice the TI pin. I will revisit the C&S pin again, as my testing before was before smoothing things up. Now that the gun is smoothing up, I think I can accurately assess a longer fp.

Thanks again,

Craig

 

[tomcatt51]

My reamer came from Brownells #184-051-450WB.

"CLYMER407 45 ACP(B) FINISHER" are the markings on the reamer.

There are (or were) two Clymer reamers. Brownells used to list both. There was a "right" and "wrong" reamer for our revolvers and you had to be carefull which one you got. I talked to one of the tech guys at Brownells when I bought mine but don't remember why one was "wrong". That was seven or eight yrs ago. They now seem to just list the 184-051-450WB

It hasn't "dropped" into any 625-8 chamber I've seen. All had to be reamed for the reamer to go in deep enough to touch the "ledge".

The chambers have had to be reamed before my chamfering tools' .45ACP pilot would enter the chamber far enough to allow chamfering the mouths.

If your chambers don't need reaming (and if the reamer, assuming you have the right reamer, will drop in and sit on the ledge they don't need reamed) so be it but they'd be the first 625-8 I've run into that didn't.

As to headspace, they're definitely meant to headspace off the moonclips. As I said, drop a new piece of brass into a chamber and check the headspace. Then check the headspace with brass that's moonclipped. I've been seeing ~.015" MORE headspace on new non-moon clipped brass (that will actually drop far enough into the chambers for the mouth to rest on the ledge) vs mooncliped brass.

I only shoot moonclipped rds. Guess I should try a few non-moonclipped rds to see if they go bang. My 625-8 (and my 627-5s) has a 5 1/2 lb DA pull and is DAO.

Just FWIW.

 

[Bearbait in NM]

Tom,

Great info. My reamer is marked "45 acp finish clymer 7/8. The Brownells number is 184051450 with no wb. Also the Brownells part number is on the Clymer label, not on the yellow Brownells label like my others. methinks I have the alternate for the cylinder. I am very certain mine would cut the ledge if not extremely careful.

But you note on the gauges rung my bell. I just checked with feeler gauges between the case head of a loaded round and firing pin bushing. I had meant to do that at some point between clip brands to just get a feel.

With a TK 0.040 Moonclip, 0.895" brass length, I am right at 0.012" feeler fitting on all chambers. With the case in on the stop shoulder (no clip), every cylinder is dead nuts at 0.015". I might be able to force a 16 in on a couple, but not appropriately.

I have no way to check roundness appropriately, but my depths look to be spot on. It also looks like if I can rustle up a 0.495 TI fp from S&W (as opposed to my 0.490), the extra 5 would be 2 over the difference of 3 thou between clips and loose rounds, at 0.895 oal which is pretty close to max trim.

Not sure what is up with my gun, as I have read scores of threads on various forums stating that all 625-8's need finish reaming, but mine seems to be right on the money. At least for depth and loose rounds fitting against the stop correctly. Probably not going to bother trying to get the correct Finish reamer, at this point. And I am really only wanting to know if a couple of brands of brass may work loose, not the entire stash I have, with dozens of headstamps ;^)

Your post was not a FWIW, by the way, it was most helpful. Thank you, sincerely for taking the time,

Craig

 

[tomcatt51]

My reamer is marked "45 acp finish clymer 7/8. The Brownells number is 184051450 with no wb.

Your part number is correct. The WB is an add on when Brownells updated their system. Mine has 184-051-450 on the reamer box. Add WB and you have the new catalog number.

I do kinda wonder about the markings on the reamer shank...

If your rds are actually headspacing on the chamber ledge, not just stopping due to an interference fit in the chamber, and your headspace is good the only thing I can say is maybe S&W is getting their act together... OR, your cylinder is an anomaly...

Either way it sounds like you're good to go. Have fun.

 

[Bearbait in NM]

Tom,

My reamer definitely has a cutting edge up to the stop ledge as looking at the reamer from the side. The ledge surface (vertical as looking at the reamer horizontal) is also sharpened. next towards the pilot is a semi-circle recess below the ledge cutting surface, and then towards to pilot the sharpened surface drops sharply to the reamer center-line. I assume the semi-circle is a place to allow chips to gather when deepening the the stop ledge, and the drop means the throat area towards the muzzle side of the chamber will not be touched. Definitely a chamber finish, without throating.

In any event, I will not be using it, unless I decide to convert to 460 Rowland ;^) Just joking there, as I think Rowland pressures would beat the gun terribly. I can reload 45 Super to safer levels.

Whether an anomaly or someone was paying attention on the CNC, I think they really got things correct. My endshake is less than I can accurately measure. I am not good enough to "feel" less than a thou differences. It is less than 0.002 and feels like 0.001 when trying to read my feeler drag.

I wish my BC gap was less than 0.007, but the cylinder is square to the forcing cone on all cylinders, and it looks like I can tolerate a little loosening of endshake over time, and still be able to shim within S&W specs of 0.011.

The bolt is hitting the notches correctly on all of them, and it had the tiniest of burrs on the stop side of the notches. I have not dressed those down yet, as I wanted to see if they got larger. Even with very heavy loads, not getting worse. And my front sight is as vertical as I can discern ;^) Cylinders are all at least 0.452, but less than 0.453 as best I can measure. 0.452 lead bullets are a snug push through.

As I noted, it is a late 2013 gun, so fingers crossed it is not an anomaly.

Craig

 

[tomcatt51]

Whether an anomaly or someone was paying attention on the CNC, I think they really got things correct. My endshake is less than I can accurately measure. I am not good enough to "feel" less than a thou differences.

I wonder if your cylinder was simply cut with fresh, sharp cutters and as we've speculated S&W simply tries to run the cutters too long between changes?

Anyhow, since you mention endshake, I take new guns and first thing cut the yoke back to accept a .004" endshake bearing/shim. Doing this protects the bearing surface down in the cylinders yoke bore preventing the the end of the yoke from wearing a groove in that surface.

That groove is hard to remove and is where future endshake develops. The shimmed cylinder will stay in spec much longer than one without. While virtually no endshake is good on lower rd count, higher pressure cartridge guns, .002" - .003" is a lot less finicky and more practical in a gun you want to put a bunch of rds thru between cleanings.

 

[Bearbait in NM]

Tom,
Interesting, I had not heard or read about cutting and shimming as an initial step as preventative. In my case that would move my BC gap to something close to 0.009 with a close fit, probably 0.011 if I went with a 0.004 and 2-3 endshake. So far my tighter endshake has not been a problem with my shooting habits.

I would assume that you would also need to check the bolt and cylinder notches if doing this work? This might also start to mitigate a stock 0.490 firing pin length?

I'll give this some serious thought.

Thanks,

Craig

 

[tomcatt51]

Tom,
Interesting, I had not heard or read about cutting and shimming as an initial step as preventative. In my case that would move my BC gap to something close to 0.009 with a close fit, probably 0.011 if I went with a 0.004 and 2-3 endshake.

I'm not sure you're looking at this correctly.
B/C gap is checked with the cylinder held back. MORE endshake will give a lesser B/C with the cylinder pushed forward by the amount of endsahke.
LESS endshake will KEEP the cylinder backwith more consistent, lesser' headspace.
If you have .011 B/C gap now with the cylinder held back, .002 - .003 endsake would still give you .011 with the cylinder back and .008-.009 with the cylinder forward.
I've "fixed" enough grooves at the bottom of the yoke bore that I do what I can to prevent them by using the bearings/shims.

I would assume that you would also need to check the bolt and cylinder notches if doing this work?

Won't appreciabley change.

This might also start to mitigate a stock 0.490 firing pin length?

.002 - .003 endshake and .495 firing pins works fine. Firing pins under .492 I throw in the garbage.

I consider endshake tolerance as a practical matter. My lower pressure high rd count guns get more. They're usually match guns and need to run reliabley and be reloaded "on the clock" and a little crud under the "star" on a near zero endshake gun can be a real problem. I have a 686-5 going together for silhouettes, IHMSA FPAS. It has lesser endshake.

Note: When you check endshake do it with the yoke screw removed or you'll get a false reading.

 

[Bearbait in NM]

Tom,

Yes, I do understand what endshake is theoretically, but I clearly do not understand what bears on what with regard to the cylinder and yoke. I've got a video coming in, have not been able to find a copy of Kuhnhausen, yet. Thanks for trying to set me straight. I have a couple of generic revolver gunsmithing books in a box in storage, I better dig them out.

I am not at all concerned with the gun running tight, I am more concerned with doing whatever it takes to minimize "battering" with heavier loads, and tweaking the DA pull to get it as low as possible with CCI primers. I like them with my Super loads, and I have many thousand of them.

I am having zero luck finding S&W stock firing pins or springs to fiddle with, but I do have a couple of Apex pin/spring sets coming in. Between those, my C&S pin and my stock S&W, I will be able to test and tweak. My hammer shims and endshake bearings will be here by Friday.

Thanks,

Craig

 

[Bearbait in NM]

Another update. Tom, you sure know a bit about action jobs ;^) I installed the hammer shims (the triiggers are not yet here) and was able to get down to 7.5 DA exactly as you noted above. I did have a small rub of the left side of the hammer on the internal lock plate. The hammer obviously "feels" more solid now,

I had previously noted hearing a hollow "tink" sound when fry firing. I would not always hear it, just occasionally. Now with the hammer shimmed, it is every single time. It's the hammer now properly hitting the frame at the firing pin.

I tested the new Apex firing pin last night with CCI primed cases here at home. It came in at 0.495 v. my stock 0.490. I got hand seated CCI's to ignite at 7.0 lbs, and I might have a little more room there. I need to live test with CCI's seated years ago on my Dillon with mixed brass and the hodge pod of primer seating depth. The WLP's hand seated almost look like they are going to pierce.

The last item here is I now know what folks mean when they say you have to balance the rebound and hammer springs. While 9lbs DA worked with a 12lb rebound, now that I am closer to 7 DA, the actions just better. It feels like a single smooth cycle now, if that makes any sense.

Thanks again for all of your help,

Craig

 

[tomcatt51]

Thanks again for all of your help,

Glad it worked out. It's not hard to do but attention to detail is important. The little things count.

 

[bimmerland]

Bought the Wolff reduced power kit and had constant light primer hits with CCI. Since my 625JM was built in 2014 I found out that my stock hammer spring it adjustable via the strain screw. Learned a lesson about using the wrong loctite but thankfully a little heat from my soldering iron loosened the screw and saved my butt. Started slowly tightening the screw until I reached 8# DA . Used a modified way of measuring the exact length of the screw to get my DA tension. Since I'm into model airplanes I had a bunch of very small lock washers and found one the correct lenght to lock in my hammer spring tension. I now have 8# DA and about 3# SA. CCI issue resolved. The last issue was the pachmayr presentation grip screw binding on the hammer spring. A little filing to reduce the diameter of the screw center fixed that issue. So final results were keeping the Wolff 13# rebound spring and the stock hammer spring. Very satisfied with results. Made a great gun even better. All the info on the forum is what makes these projects possible. Thanks.

 

[Bearbait in NM]

Bimmer,

Yes, it is a process. I am still tinkering with CCI primers, mixed brass and primers set on a 550b. Now that I am going to be shooting 45's again enmass, I decided to dig my 550B out of storage.

Funny you should mention the grip screw binding on the hammer spring. I too found a set of pach's to be very very close. As the grip is a lousy fit, allowing the gun to rock some in the grips, I decided to not use them. I have a set of Ahrends combats that fit my hand well, and the screw clears properly. I wonder how many folks out there have some degree of this problem ?

Craig

 

[tomcatt51]

grip screw binding on the hammer spring.

Haven't personally seen this for a while but it does happen. If I remember right, usually because a stock, flat, mainspring is being used with a shortened strain scew vs a spring with more arch.

Spring arch is important regardless of if it's bent into the spring or the result of greater preload from the strain screw. It maintains the correct hammer strut/link geometry.

The difference between the Wolff std and reduced mainsprings is just the amount of arch.

 

[Bearbait in NM]

Tom,

The factory grips with my gun has the grip screw very close to my Wolff spring. Close enough that I had to check it for myself. The Pach's that I have run the screw on the inside of the spring, relative to the others that I have that run on the outside (rear) of the spring. I have made lots of grips for various guns over the years, so perhaps I am just anal about checking it ;^)

I kinda wonder about this, as the arched hammer spring is somewhat "new" relative to the age and quantity of makers of some of the grips that are available for our guns.

Craig

 

[tomcatt51]

I kinda wonder about this, as the arched hammer spring is somewhat "new" relative to the age and quantity of makers of some of the grips that are available for our guns.

All mainsprings are (or should be) pretty similarly arched when installed. There's a position the end of the spring should be in for the hammer link or strut to have the correct geometry. This is why we bend the flat springs or install springs like Wolff's reduced power that has more arch so when installed and preloaded the link/strut geometry is correct.

We run into problems with shortened strain screws with the stock flat spring because it has less installed arch, the end of the spring is in a different spot and it screws up the link/strut geometry. It can also create issues with the grip screw 'cause the center of the less arched spring is in a different place.

Pull the grips and the spring arch on my 5 1/2 lb guns looks much like the arch of a stock flat spring with a stock strain screw.

I have some (Pachmayr I think) grips that came with grip screws whose center is reduced in diameter for spring clearance. Seems they just put the screw in the wrong place and a different screw was cheaper than altering the mold?

All my revolvers have Herretts' grips and don't have issues with the spring hitting the grip screw... The original grips don't have problems either.