625PC Hammer weight Adjusting

[Bearbait in NM]

Greetings, and I hope this is in the correct forum. I recently purchased a new 625PC in 45 ACP. It's my first S&W revolver in quite a long time. I have am having trouble getting Kuhnhausen's book right now, but I want to fiddle with the hammer weight, mostly in DA. I have read many hundreds of posts over the last couple of weeks here, in helping to choose the gun, and understand hammer weights v. primers. Not new to triggers or smithing, just new to S&W's.

For the current spec's, the strain screw is tight, and it has the ribbed main spring (Wolff?). Double action is 11 lbs 4 oz. Single action is 4 lb 2 oz. I picked up the Wolff Reduced Power Rebound Sprink Pak, with weights 12-16 lbs all marked reduced.

The first question is would anyone know what the stock rebound spring weight would be? And I assume this spring will not affect primer strike, only the net DA pull weight and the reset speed? The only way I can figure to test would be diaassemble, replace, reassemble and check the pull weight. Knowing the stock spring spec might save me some work and buggered screw heads, testing all 5 weights ;^).

The second question is after setting the rebound, and adjusting the main. My plan was to back the strain out in increments, test against CCI primers, and note the final weight that I want. I would then dress the screw head down to get that weight with it seated tight. Does this sound reasonable?

From what I have researched here, I am thinking that I can knock perhaps 2 pounds off the DA pull, and likely be safe with any primer. And FWIW, I was shocked the factory DA pull is over 11. My experience is with Colts, and it feels a whole lot lighter than 11.

Thanks,

Craig

 

[Muley Gil]

Welcome to the Forum.

IIRC, the standard factory weight is 18#.

 

[surveyor_nm]

Welcome, Craig...from NW NM

Bill Mahnke
SWCA #1915

 

[Bearbait in NM]

MG,

Thank you, that makes sense, as even the 16 is marked reduced. I was kinda wondering as the PC revolver uses what appears to be a Wolff mainspring (they look the same) and I wondered whether the PC may have used a lighter rebound spring.

Bill, small world. I am a Surveyor in north central NM. Scratching my head trying to remember whether we have crossed paths. Looks like Snoopy needs to stand on his doghouse to see through the transit. Lord knows I have stood on "stuff" to see through my gear at times ;^).

Thank you both, looking forward to spending time here.

Craig

 

[retired2006]

Why not use some blue lock tight on the stain screw, back it out to where you want it, and the lock tight will hold it there, I do it all the time. If you do that you can always return the revolver to original if you want to.

 

[surveyor_nm]

Craig,
PM sent

 

[BlueOvalBandit]

The second question is after setting the rebound, and adjusting the main. My plan was to back the strain out in increments, test against CCI primers, and note the final weight that I want. I would then dress the screw head down to get that weight with it seated tight. Does this sound reasonable?

This is the way to do it, by counting revolutions of the screw backed out the, plugging it into a formula to convert revolutions to inches based of the pitch (which I forget right now), then filing the strain screw down. You can play with the arch in the mainspring but it's less straightforward.

 

[Johnnu2]

S&W trigger weights

Disclaimer: I'm old and haven't worked on any new S&W revolvers; however, I'm old and have worked on many older (1960-1970's) S&W revolvers. I was taught never to mess with the strain screw or mainspring. All the weight for a single action/double action trigger adjustment can be accomplished by changing only the trigger-rebound spring. I've set my K38's to two pounds for casual target work simply by changing that spring (and maybe a little light stoning on the rebound-spring block. When I was young, all the old guys always stressed leaving that strain screw all the way in and not messing with the main spring tension. J.

 

[Bearbait in NM]

Thanks again all. Retired, I have no problems with loctite in general, my thought is that as I usually take the grips off when cleaning, I like the idea of just throwing a screwdriver on the screw, and giving it a snug.

John, that is interesting. Again, I have not been able to come up with a copy of Kuhnhausen yet, but the rebound spring is going to be my first change. I would never fiddle with the spring, as I now have spares, and I like the idea of just swapping out to a new spring when what is in the gun gets tired. And that ties into either dressing the strain screw or possibly shimming, rather than loctitie. I originally thought the rebound would not affect SA pull, but upon more reflection perhaps it will. I am only looking for a pound in SA and perhaps two in DA.

In any case, my box from Brownell's arrived, so I do have some things to try now.

Craig

 

[Johnnu2]

trigger spring

Bearbait.... the trigger rebound spring is THE spring that controls the weight of pull on the trigger...Just put anyone of the new Wolff reduced power springs in your gun you will feel the difference in both single action, as well as double action weight of pull. If you have some good action 'stones', a light dressing of the block that houses the trigger rebound spring will also make a shocking difference. Pls. let me know how you did with your 'action job'.... J

 

[Bearbait in NM]

John,

Thank you. That does make sense, although there does appear to be differences in the main spring. My PC gun came with a ridged mainspring that looks suspicially like the one that also came in a Wolff action kit. My problem is that this is my only S&W revolver, so I am not sure if my main is different than what ships on others.

YES, I will absolutely update this thread. You all have been great. Got sidetracked this week, and will be derailed this weekend, as well. My plan is to methodically change things out, record everything on my trigger guage, and report everything. About all I have been able to do this week is dry fire the heck out of it, now that I have my snap caps. Thinking that I want things on the gun "settled" in a bit, so the dry firing is probably a good first step.

Craig

 

[Johnnu2]

trigger

Good thinking on the dry firing... Certainly will help provide a good baseline. I don't know about originality of your main spring; haven't ever opened a newer S&W. GOOD LUCK and enjoy the project, I know I always love to tinker. J

 

[don p]

I have used the Wolfe reduced power spring and have mis-fires.
I now have a Wilson reduced power spring, reduced rebound spring, some polishing and now have a 7 lb 8oz double action trigger pull on my 625-8.
You will need to use Federal primers in your reloading. They are the softest primers on the market. By the way the screw for the hammer spring is locked down and NOT backed off at all.

 

[Bearbait in NM]

OK, was up late last night, getting some numbers. I'll start with the specs.

625 PC s/n CUZ05xx (supposed to be new on GB, looked new but it could be older but unused)
Firing pin 0.490 in length, went ahead and chaged out to .510 C&S
Hammer main is ribbed with curved forks at top

Here are weights as averages of at least 6 pulls with my Lyman
(weights are in lbs and decimal oz's, DA then SA) gun mounted in a vice trying to be very repeatable with guage technique:

Stock: 11 11.2 /// 4 6.2
Strain out 1 Turn: 9 10.0 /// 4 1.0
Strain out 1.5: 8 8.2 /// 4 0.1

Wolff 15 Rebound: 11 7.8 /// 3 5.2
15, 1/2 turn out: 9 9.0 /// 3 6.3
15, one turn out: 8 11.7 /// 3 7.1

Wolff 12 Rebound: 10 15.0 /// 3 11.1
no further testing, as trigger return was terrible at 12.

My thoughts. I thought the return spring would be more dramatic as to weight change v. pull weight. Gonna try to stay with 15, as the return feels good. I did try a replacement M25 strain screw (blue) but it was well short of my stock SS. Gonna stay with the Wolff stuff, as I also now have a new Power Rib 2 to recheck as above, and an additional spring set. Not gonna dress on my stock strain until I can get a correct spare. And I need to find the minimums with all primers going bang, in clips and single loaded. Not gonna make the gun brand specific.

Another thing I found out last night once I had my pull weight down to the three's SA, is that my overtravel trigger pin is very short. I could catch the sear break at least a 1/16th inch before the stop hit. I need to test more and perhaps address. I have quite a few guns on various platforms with stops, and this one seems incorrect, even allowing for some safety margin.

Craig

 

[Johnnu2]

trigger springs

Craig, from the info on this Jerry Miculek video, and from Blue Oval Bandit, I stand corrected re: adjusting the strain screw/main spring along with the rebound spring.. hope this video helps (there are also some other videos on You tube that are specific to the 625, but this is THE MAN working a mod 10.... How to install a spring kit (trigger job) with Jerry Miculek - YouTube.... John

 

[Bearbait in NM]

John,

Thank you and I had looked at that video. His tip on using a BIC pen to reset the rebound and spring was pretty handy last night ;^). That video was part of my reason for asking my initial questions, and confirming methodology.

Not saying that I do not trust JM on his approach, but much like what was probably correct back when you were smithing, "accepted" techniques probably evolve with time, and use for the gun. The old competition v. carry/duty in particular. I did not miss Blue's post, but I would be concerned about doing the math for a final cut. I am thinking I will either use loctitie or shims under the screw head, and dress the tip at the range while confirming ammo and my trigger pull guage. Leave myself the ability to lower the screw just a bit to account for wear in the mainspring.

I hope my numbers post above kinda helps show that there are a couple of ways to skin the cat, combining the rebound and main. I was surprised last night while fiddling with both how much different the gun could feel. Not just light, but including the rebound. I knew right away that the 12lb rebound felt awful, with such little rebound action. And the 12 bought me very little on the overall weight.

Thanks again,

Craig

 

[teezer]

what i did 30+ years ago, when playing with the actions, was to apply automotive valve grinding compound liberally to the action and sit and dry fire a zillion times. i would then open it back up and look for the bare or thin areas of compound and thusly concentrate on them with more compound and dry firing again.

smoooooth


..

 

[Bearbait in NM]

Teezer,

Times have indeed changed. I think the preferred method today by the Cowboy Action shooters is to use toothpaste to do the same. And I think they are specific about it being Crest ;^) And Crest would be cheaper than JB Bore Paste......I got past my assembly panic last night when the spring fell out of the trigger, when removing the hand. I'm gonna address the innards after getting the spring weights sorted. And I did indeed ponder Crest or lapping paste of some sort. seriously.

Craig

 

[usnrigger]

I don't believe in dressing down the strain screw to lower trigger pull. I do all mine with about 2.5-3hrs of stoning with a fine India, Hard Arkansas, Ruby Stones and Spyderco Ceramics. I also make sure to de-burr surrounding parts as I go. I do make sure it will run CCI's as they are harder then most. also making sure the cylinder rotates with ease will help DA greatly.

 

[teezer]

i picked up a model 19 a few years ago and wanted a smoother action. ordered a set of Wolff springs that had 13, 14, 15# rebound springs in it, didn't like any of them. took the 15# spring and cut 3 coils off (remember to put the cut end in the block) and was very happy with the result. the strain screw remained tight.

i still would use valve compound over toothpaste as it's made for metal work, and way to many choices of Crest on the market


..

 

[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.