Problems with my 645 - Slide staying open after most shots =PROBLEM SOLVED!

[mzack66]

Hi guys -

I'm having problems with my 645. I was getting (all of the sudden and out of the clear blue) FTE's. The ejector looked fine, so I sent it to S&W last JUNE, and due to their backlog, I just got it back this week. Off to the range I went today.

Now, I'm getting a new problem, some failures to chamber, (Winchester White Box 230gr) but worse, my slide is locking up with the slide stop after many shots?? I ran a few mags through and they all did this. That is, until I ran some of my 200gr SWC hand loads. I loaded these softer, 4.2grains of bullseye, and each fed, ejected and shot fine.

I'm wondering if they did something to my recoil spring? It felt like there was more muzzle jump with every WWB round. I don't have any spare springs, so I ordered a wolff set to try a new spring. I've never had the slide lock back and open with the slide stop catching it ever before? Am I on the right track with the spring being weak?

By the way, S&W didn't include WHAT they did to my gun, just that the "repairs FTE issues".

 

[handgunner356]

That 4.2gr load is pretty light and if it's cycling fine you might be on the right track. But I've never known of Winchester White Box to be all that hot either. I would take the upper off and just set the slide stop lever and the recoil rod back in the frame and see if the plunger in the end of the rod is contacting the lever and giving it a bit of downward tension.

 

[mzack66]

Thx. I'll take a look at that. It seems after studying it a bot more that the slide lock doesn't have a lot of tension on it, and may be "jumping" up and catching the slide slot to hold it open as if it were pushed up by the mag when it's empty?

 

[mzack66]

I just broke it down, thanks, I understand how the guide rod puts pressure on the slide stop now. It is putting pressure on it, albeit, it doesn't seem to be a lot, but I guess it shouldn't. The guide rod uses a small nipple that protrudes from the rod through the frame to apply pressure on the flat milled part of the slide stop. That nipple is spring loaded too. Lacking a new recoil spring, would it be generally okay to "stretch" the recoil spring some and give it a try at the range? I'm not wondering if I don't need a new guide rod, thinking the internal spring may be weak.

 

[Denver Dick]

I can only think of two other things. First, be sure the slide stop plunger is present and that its spring is providing some pressure. The plunger works against the side plate. The side plate has a little angle which works so that the pressure from the plunger provides a small bit of downward force to the slide stop. Second, if you use a two hand hold, be sure a finger or thumb is not in a position to touch the slide stop under recoil. Other than those two things (and the points discussed above), I can't think of anything. Good luck.

 

[mzack66]

Thanks. For my assurance, the slide stop plunger is the spring loaded nipple on the end of the slide stop? I think it is, and it is indeed present and under some pressure. And is the side plate dose seem to have a a very little angle to it, and the slide stop plunger is making contact. I *almost* considered the trying to bend the side plate toward the slide stop plunger a little, thinking I could "tighten" the fit, but it appears to be about the same as others I can see in some pictures. Damned frustrating. I can't believe this didn't happen when it was test fired at S&W. I'll recheck my hands, but I've been shooting this rig for 2 decades and haven't changed my grip too much. Worth thinking about though, thx.

 

[mzack66]

Ok, I went to the range, and at least I now know why the slide is staying back with many rounds, and why it was happening with my factory 230gr round nose, and not my 200gr SWC reloads: The second bullet (next in line in the mag), is hitting the slide stop actuator as if the mag was empty. What's happening is, the next bullet to load (first in line on top) is slipping forward in the mag about and 1/8" or slightly more from the recoil, allowing the next bullet in line under it to come up a little higher than is should, and act like the magazine catch meant to lock open the slide when it's empty. It doesn't so it with the SWC because the bullet profile is such that it allows for clearance. Now the question: Does that simply mean my mag springs are bad? It did the same with all 3 mags, they are all old and used in rotation.

 

[Denver Dick]

Oh wow , a blast from the past. I had forgotten that I had that happen years ago. It was with one or two of my .45 ACP pistols. However, I have had so many .45 ACP pistols over my 42 years of shooting them that I can't recall whether is was a Colt Government Model, Colt Combat Commander, Springfield Armory 1911 or one of my S&W .45 pistols (4516-1, 4516-2, 4566, 4576, 4506-1). I'm pretty sure that one was the Combat Commander I had back in my mid 20s. Actually, now that I think of it, it also happened with my S&W Model 1076 over five and a half years ago (maybe that's why it was on consignment in 99%+ condition for $450 ).

In each case, I determined that the slide stop was a little (very slight) different from others. The bullet was more rubbing against the slide stop as opposed to getting under it and pushing it up, i.e., there was very slight contact. I cured the problem by very lightly stoning the part of the slide stop that was causing the problem. In the case of the 10mm, it took very, very little stoning. In the case of the Combat Commander, it took a little more.

Now if you decide to try the stoning approach, I suggest you keep two things in mind. First, you must not stone off too much because the part must still perform its primary function. The second thing regards the use of stoning. I always have an excellent Arkansas Stone and honing oil on hand. Using a quality flat stone allows one to remove a little metal without changing any angles. I recall that I would take a tiny bit off and then check the results at the range. If it needed more taken off, I would do so then back to the range. Doing it a tiny bit at a time helps assure that you don't take too much. I think it took me two or three trips to the range to get it perfect.

Of course, you could always just buy another slide stop, but you could end up with the same problem.

FWIW and good luck.

(I don't think it will turn out to be mag spring, but you should try new ones first before touching the slide stop. I my case it happened with fresh strong springs. S&W may have put a new slide stop in when the worked it over and the problem just didn't show up on the mag they test fired. Keep in mind too that 230 FMJ bullets by different makers may have slightly different angles and radiuses. Have you tried other 230 FMJ? FWIW)

 

[yeti]

Yes, it sounds like new mags springs are in order. Stock or the Wolff Extra Power work nicely, but it kind of depends on who's got what in stock.
Take apart the mags and clean then up well. Check the mag spring orientation & the followers for tilt and wear while your at it. Does your slide stop look good?

 

[t-bird]

Would love to see some pics of your 645 mzack66

 

[mzack66]

Thanks all. It does seem the slide stop is just rubbing the bullet enough to kick it up. The size/radius of the bullet profile might explain why I can go through 2 or 3 rounds and have no problem, then all of the sudden it stays open. I measured the WWB ammo when I got home, it's consistently 1.26 COL, and the Remington is 1.245 ish. The WWWB presented the problem more often than the Remington, and my hand load plated SWC cycled perfectly every time, no problems at all. So I'l thinking they may have swapped out my slide stop for some reason, and it may need to be fitted. I grabbed 2 mags last night from a friend who has the same gun, and I'm going to go to the range and try them, if that doesn't solve it, I'll stone the slidestop. There seems to be A LOT of meat on that particular part, and it sort of "hooks" on the mag follower after the last shot, so there's definitely room for removing some material. I'll post some pics. The funny part is in all my years of shooting this gun, I have never ever had a problem like this. It seems awfully suspect it shows up after going back to S&W for an ejector issue….

 

[Denver Dick]

I currently own 34 center fire semi-automatic pistols, 19 are S&W 2nd and 3rd Gens. Since I started shooting pistols, I've probably had another 50 pass through my hands. Out of all those pistols, I've only experienced this problem twice. I vaguely recall a third, but I'm not sure. So, it's not common at all.

Keep in mind that your 645 and my 1076 are pre-CNC machining. Frames and parts can vary. That being said, you got me thinking so I went out and pulled my 1006 and 1076 out of the gun safe. Both the 1006 and 1076 were manufactured/shipped in 1990. The 1006 has its unaltered slide stop. The 1076 is the one I had to stone. I took some measurements with my calipers. It looks like I ended up taking off between .011" and .012".

So you can better understand what I did and the results as far as slide stop function after the stoning, I have included some photos. Please pardon the fact that the 1006 is pretty dirty. I haven't cleaned it since its last outing. However, this made it easy to differentiate between it and the 1076. Here we go:

First are two views of the unaltered 1006 slide stop

Here the same two views of the 1076 slide stop after stoning

Here is how the unaltered 1006 slide stop fits in relation to the magazine follower

Here is how the 1076 slide stop after stoning fits in relation to the magazine follower (note that even after stoning off metal, more of the slide stop comes in contact with the follower)

As an interesting aside, note the difference in the thumb gripping area of the two slide stops. It appears they remove some of the gripping area on the 1076 to facilitate operation of the frame decocker.

 

[Fastbolt]

We're getting into an area that hasn't been taught in armorer classes for a while, which is "adjusting" the slide stop lever assembly.

Before you start stoning on the lever's inside tab, take a look at the relationship of the lever body against the outside of the frame, between the lever and the frame. There ought to be a narrow gap that's consistent along the length of the lever.

This was discussed in at least my first class, and we were told to check for an acceptable gap between the outside of the frame and the lever.

While armorers aren't given a gauge for this (I've been told factory production used to use a gauge they called a "lollipop" gauge, but I've not seen one, myself), we were told we could use a business card to check the gap. We were told to take a standard stock business card (old-fashioned card stock, meaning not too thick & not too thin), fold it in half (lengthwise), and that we ought to be able to slip it up between the lever and the frame all along the length of the lever. I found it easiest to do from the bottom of the slide stop lever.

Now, if the gap was too wide at the back of the lever it could affect tension of the lever's plunger against the sideplate, and it it became too large, the plunger might actually slip over the outside of the plate. This would also probably mean the lever's inside tab wouldn't stick into the frame/magazine far enough to consistently engage with the follower at some point.

If the gap was tighter at the rear of the lever/frame clearance, then the lever's tab would stick too far into the frame/mag, and feeding issues could occur (as the tab bumps the rising bullet noses). Some rub marks between the back of the lever and the outside of the frame may also be observed if the lever/frame gap is too tight and the lever is rubbing against the frame at times.

Both of these issues could be the result of the 90 degree angle between the lever body and slide stop pin (post) either increasing or decreasing. FWIW, we were told that this could occur when higher pressure ammo was used (+P or +P+, depending on whether it was 9mm or .45 ACP), as the recoil forces propagate in all directions, and might in some instances cause the slide stop lever assembly to take on a bend over time, either inward or outward.

The correction taught in that earlier class? We were shown how to look for the direction the lever might have to be adjusted (inward or outward to restore the 90 degree angle between the lever and the pin), and then position the lever assembly in a small vice (not as easy as it sounds, depending on the direction the lever might have to be gently moved) ... and then carefully & judiciously whack it with a lead babbitt.

They also made us disassemble the slide stops (roll pin, plunger & spring) and replace any of those parts that may have become damaged.

Nowadays they simply tell armorers that if they suspect a defective slide stop assembly, to just replace it with a new one. No more adjusting of angles, and no more disassembly to replace small parts. Probably because it's easier to teach armorers to do parts replacement, and that takes up less class time (shorter classes, too).

Have I had to adjust a slide stop assembly to increase or decrease an angle in a well-used gun? Yes. Ditto replacing the plunger spring and roll pin in a gun that had experienced some corrosion after immersion in salt water (without the user telling anyone it had happened until about a year later ).

I've also had to replace a couple of new slide stop assemblies in new production TSW's because something about the specs of those pins, in those frames, was creating some functioning issues. Easier to replace the lever assemblies than spend time trying to diagnose subtle differences (presuming you have the spare assemblies, of course). Not surprising if a lever assembly pulled from one gun would work just fine in another gun, though. Parts is parts, sometimes.

Anyway, adjusting (stoning, changing the sharpness/angle) slide stop lever's inside tab is also an old repair trick sometimes needed on an occasional 1911, so it's not like we're breaking new ground here.

So, if it were my 645? I'd check for an even gap between the lever & frame before I started adjusting the bottom inside tab surface with a stone. If the lever/frame clearance is tight at the rear of the lever? The tab might be positioned just a bit too far inside the frame/mag.

I'd also keep in mind that removing metal is MUCH easier than adding it if you remove too much. It doesn't take much to correct a long tab hook, either by adjusting the lever/pin angle or stoning the lower edge of the lever's tab. A couple of times I've just lightly stoned off and dressed a rough edge or burr in that spot.

If you see jacketing rubbed off on the lower part of the tab, it might be due to excessive contact with the bullet noses as they rise past it.

Also, sometimes it's easier to simply use different ammo, or a different production lot of ammo, if you suspect a spec/tolerance issue on the part of the ammo.

Just some thoughts based upon the insights offered by Dick, and some experiences of mine.

Naturally, trying to "adjust" something without knowing what you're doing, and hopefully having some experience in doing it correctly, may cause more damage than already exists, or even create damage where none existed in the first place. Slide stop assemblies aren't one of the commonly stocked parts assemblies at this time, and may be harder to get than you might wish. New ones come in either plain stainless finish or black stainless finish. Pick a color. They're cast & machined/finished parts, last I heard.

 

[mzack66]

You guys are awesome, thanks for all the info. This morning, I looked at the assembly very carefully, and intuitively looked at the relation between the slide stop and the frame. It's parallel, and, the gap is very even for the entire length of the slide stop. Reading this now, I'll bet it's about a business card gap, so it may be a little close. I've never shot any hot loads or P+ loads ever, but I suppose it could wear. I decided to stone the slide stop tab, and much like the pictures Denver Dick provided (thank you) I had to remove quite a bit to get the clearance I thought I needed. I stonned, refit the slide stop into the handle applied some pressure with the recoil rod by hand, and loading different 230RN's in each mag and tried them for clearance. Longer COL's were pretty consistent with WWB (over 1.26) so I stoned to them. Well, I have success! I just got back from the range, and 200 rounds, Remington's, Winchester White, and my hand loads all in 230gr RN and they all went off perfectly, and with no issues what so ever. When the mag is empty, the slide stayed back. Like Dick's pictures, there is plenty of tab/hook left to get bumped by the activator when the mag is emly, but I seem to have sufficient clearance for 230gr ammo again. I'm so happy, I really love this firearm and was pretty upset after getting back from S&W not working. I think they assembled it with another slide stop, I've owned this gun for ever, and not once had I ever seen this issue. In fact, before the FTE issue I sent it up there for, I don't think I've ever had a hiccup with this at all! Anyway, I'm really happy, thanks for all of the advice, and happy shooting!!!

 

[Fastbolt]

Glad it worked out well for you.

Now, bear in mind that the bottom of the lever's inside tab can eventually wear down the thin edge of the plastic follower's open tab notch (if that's what you're using), and replace the followers if you start to get failures of the follower to rise and lock the slide back on an empty mag (because the thin ledge got chewed down).

If you're using the original old-style 645 mags? I'd leave them for range use and consider picking up the current mags (black plastic followers & butt plates). Revised and improved lips and mag body design, a better spring and overall an improved mag. Helps make a good gun better.

Congrats.

 

[handgunner356]

There was also at least 4 revisions to the 45 mags, some of these were to help hold the top round back. The yellow follower tubes had indents at the rear of the tube and the newest black follower has indents at the top along the feedlips. I never had any problems with the earlier mags but I usually just shoot SWC style bullets.

 

[mzack66]

Thanks! I still have 3 original metal follower mags, and I have 1 "orange" plastic follower mags. I see what you mean on the edge potential to wear the plastic follower. I'll have to get some new mags (if and when I can find any!). Looking at it now, it seems the slide stop is slightly tweaked, which made the slide stop tab protrude in too far, so it could have been bent back out instead of stoning, but what's done is done, and to works great so I'm happy. Man, that's the last time I send something to S&W...

 

[Fastbolt]

There was also at least 4 revisions to the 45 mags, some of these were to help hold the top round back. The yellow follower tubes had indents at the rear of the tube and the newest black follower has indents at the top along the feedlips. I never had any problems with the earlier mags but I usually just shoot SWC style bullets.

Yeah, I ended up inheriting a bag of the early 645 mags several years ago. I gave them away to 2 or 3 guys to use for extra range mags, as they all had full-size S&W .45's.

Just the other day I saw someone using an older revision 3rd gen .45 mag with the yellow follower and older body, so I replaced it with a new 3rd gen mag (since it was being used for carry).

 

[Denver Dick]

. . . Anyway, adjusting (stoning, changing the sharpness/angle) slide stop lever's inside tab is also an old repair trick sometimes needed on an occasional 1911, so it's not like we're breaking new ground here. . .

HA! You caught me. I use to own many 1911s, and did my first stoning on a nickel Combat Commander in my mid 20s. Boy it was a pretty thing. Since I bought the 1006 and 1076 at the same time, I did try exchanging the two slide stops before my stoning, and sure enough, the 1006 slide stop did the same thing as the 1076 slide stop when installed in the 1076.

Your information regarding gap and lever/frame clearance is great. Of course, now I have something more to be checking on my many 3rd Gens. Now, let's see, where the heck did I put my old business cards.

 

[Fastbolt]

... Man, that's the last time I send something to S&W...

Well, let's not get too far afield.

Things can slip by, especially border line clearances, combined with the variability introduced by ammo spec variations.

There are some problems that it takes a factory repair tech, gunsmith or armorer to properly diagnose and correct.

While most of the parts are drop-in (but require bench checks to confirm fit & function in any particular gun, due to tolerance issues, especially when it comes to "pre-CNC" guns), some aren't. The extractors require fitting, and older .45's may even require some additional fitting not normally needed in newer guns. A Go/No-Go bar gauge, too. Checking extractor spring tension involves using a rather pricey force dial gauge, as well.

If the gun starts experiencing failures-to-decock (or hesitation, before failures), then a new sear release lever has to be fitted (more filing, and a couple of factory angles for the lever foot have to be carefully maintained during filing).

Don't write off the need for factory repairs just yet.