45acp revolver and light primer strikes

[MifflinKid]

Try these, step by step, test firing after each.
1. Tighten the strain screw as RC suggested.
2. If you have another N frame that fires reliably, try switching strain screws.
3. Clean the chambers, recoil shield and cylinder ratchet.
4. As ClemY suggested, install an Apex Tactical XP firing pin. I had the same problem with a recent manufacture M625. This solved the problem.

https://apextactical.com/store/product-info.php?pid4.html

5. Get these and install --

http://www.brownells.com/.aspx/pid=9858/avs|Manufacturer_1=POWER CUSTOM/Product/CYLINDER_BEARINGS

6. Send it back to Smith and Wesson.

 

[RugerMcMarlin]

Are you the first owner, since it was new? Could the main spring have been switched out before you got it?

I'm leaning towards a new main spring. Do what the last post suggested and you'll be up and running.

 

[ExMachina]

@MifflinKid, thanks. As you can see I'm already up through to your step 4 and I don't have any end play (for step 5)...so if the firing pin doesn't solve the problem (with factory ammo) then the gun's going back to the mother ship.

 

[Dave T]

ExMachina,

I have five 45 ACP revolvers in my safe so I have a bit of experience at this. I have changed main springs in all of them and experienced mis-fires with all of them. When the same main springs are used in 357 Mag and 44 Special N-frames I have no problem with mis-fires. That led me to believe the problem wasn't the lighter/smoother main spring but something else.

It's an old truism in reloading that a partially seated primer will generally mis-fire because too much of the firing pin's momentum is used up (robbed if you will) seating the primer to the bottom of the primer pocket. By the same token, I believe the play that exists in a full moon clip robs too much momentum from the firing pin leading to occasional, and in my experience frequent mis-fires. Instead of going back to heavy double action trigger pulls, I switched to Federal primers. The problem went away in all five 45 ACP revolvers.

May not work for you but I pass it along for your consideration.

Dave

 

[rcmodel]

All these problems started when S&W changed to the frame mounted firing pins.

At about the same time, they also stopped chambering them to headspace on the case mouths without moon-clips, like a 1911 .45 pistol.

Prior to that, any .45 ACP S&W revolver (1917, 1950, 25, 625) would fire any primer, with or without clips.

Now, most of them have deep chambers & resulting excess headspace, and are not reliable without clips, and in some cases, even with clips.

Spring tension looks to be maxed out: the mainspring is flat against the frame and does not look like it can be tensioned any more.

That doesn't sound at all right to me.
Sounds like somebody ground off the strain screw.

When properly tensioned, the mainspring should be bowed away from any contact with the frame except where it hooks on at the bottom if the grip.

See the photos here:
Strain screw backed clear out = Spring touching frame.
Strain screw tightened Fully = Plenty of air space between frame & spring!

http://www.thehighroad.org/showpost.php?p=5000202&postcount=62


rc

 

[MifflinKid]

ExMachina, I thought of one other aspect for my number 4.

When I replaced my M625 firing pin with the Apex Tactical XP firing pin, I polished the XP firing pin (the part that protrudes to strike the primer, the barrel of the firing pin and the flat portion of the cut out area) and ran a drill bit through the firing pin bushing to remove any burrs.

I almost universally use CCI primers and 700-X powder, so my M625 needs a good whack to fire and gets pretty dirty. Also, I use RIMZ 625 polymer moon clips that some believe will soften the firing pin strike.

Last week I finished shooting 500 rounds of 45 ACP and 45 AR rounds in this M625. I started having failure to fire problems just after round 450. I brushed the recoil shield, the extractor star, the chambers and then oiled the extractor star. The remaining rounds of the last 50 fired without a problem.

Good luck on finding your problem. I know problems like these can be frustrating but in the end you will learn something and will be a better gun mechanic.

 

[RugerMcMarlin]

Can you take the strain screw out and post a picture, so we can see the screw by itself?

 

[earplug]

Soft Strain screw.

I have had two strain screws that were soft. They would distort and mushroom so that the effective length was shorter.
This lead to the same problem your having.
Get some hardened set screws from a hardware store and fit your own strain screw. I used a allan head machine screw and had to grind the head down a bit to fit the recess in the frame. But you can get a bag of screws for the price of a factory screw.

 

[cwneely]

I have a 1950 target in .45 acp that had the same problem. Headspace was excessive. It can be corrected by stretching the yoke or using a shim on the yoke barrel. This will close the headspace but open the barrel cylinder gap. You can then set the barrel back one thread. It's a gunsmith job but worth it.

 

[ExMachina]

"I have a 1950 target in .45 acp that had the same problem. Headspace was excessive. It can be corrected by stretching the yoke or using a shim on the yoke barrel. This will close the headspace but open the barrel cylinder gap. You can then set the barrel back one thread. It's a gunsmith job but worth it."

that's really good to know. wonder if S&W would cover that under warranty, even if the extended firing pin does work--might ask

(my b/c gap is already on the far side of being in spec)

 

[ExMachina]

@rc my gun looks pretty much like those pics. if anything, my strain screw could be on the long side...

 

[ExMachina]

UPDATE:

got my gun back from S&W today and there's good news and bad news.

good news:

they replaced yoke and cylinder and now the excess headspace issue is gone--went from 0.015" down to 0.008" which should be much better

bad news:

the 0.006 inches taken off the back of the cylinder have now reappeared on the front! my b/c gap is now 0.012" which is out of spec, even according to S&W's newer, more leanient standards :banghead:

why on earth wouldn't they have checked this?

so, i'm going to shoot it a little and then send it back to S&W to have them close the gap back down.

ugh. S&W's customer service is top notch, but i sure wish my brand new gun did need so much of it!

 

[RugerMcMarlin]

Did you think they would stretch the cylinder?

 

[ExMachina]

Did you think they would stretch the cylinder?

no, and the S&W gunsmith probably didn't think that either...which is what makes it hard to understand why he wouldn't have turned in the barrel after making the correction.

 

[Stainz]

Other things to check...

1. Crud under the ejector star at the ejector rod juncture. This can include a cotton swipe's thread or a bronze brush's wire bristle - but it could just be carbon crud.

2. With a Wolff 'Power Rib' spring, the turned down end of the normal length recent strain screws will intrude into the hollow rib, lessening the pre-load and giving you ftf's - and a lighter than it should be DA pull. The factory ground strain screws on my 625JM and 627 Pro were replaced with new ones, fixing the ftf problem with both. Even with the full power Wolff and new strain screw the DA pull was excellent.

I use only Federal primers now - 100% reliable. I get 1 in 6, sometimes, ftf's with the UMC 250 pack from WallyWorld. As the C&S 'extended length' fp is actually regular length - but with a wider limit notch which will yield a broken fp return spring with dry-firing, I tried it and re-installed the OEM quickly. With the fp removed, I spritzed the hole with aerosol RemOil - and some crud came out. My thought was that the crud may have slowed the fp, but I had also found crud under the ejector star then - over six years ago, when my 625JM, an early one, was relatively new. I reasoned that the crud was from manufacturing - and it is now another cleaning area for me in a new S&W.

Good luck.

Stainz

 

[ExMachina]

UPDATE:

To any and all who might be interested--it appears like it was the excessive headspace that was causing all my light strikes.

A return trip to Smith and Wesson and the headspace is now down to within specs. Result?--the gun digests EVERYthing: factory ammo and my handloads (even ones with "hard" CCI primers).

Now here's hoping that someone else can benefit form my experiences with this problem, since there seem to be several threads out there concerned with light strikes in S&W 45ACP revolvers. So if your having multiple light strikes with a full-power mainspring, check your headspace (because the S&W factory may not have ! )

Shoot on

 

[MifflinKid]

Great, good to hear your gun is fixed.

So, how is the accuracy with the larger B/C gap?

 

[ExMachina]

Accuracy is as good as it ever was. Right now, I'm most curious to know if/how much the velocity has dropped. The outside of the cylinder and area around the b/c gap was filthy at the end of the day--I've never had a (smokeless) wheel gun that was such a mess. I'm supposing that a lot more gasses are escaping now than were before.

But I'm just so pleased to have this gun finally go *bang* reliably, that I'm not going to go crazy in rushing this back to S&W...not just yet anyway

 

[Owen Sparks]

Mine is doing just the opposite. Sometimes it pierces the primers.

 

[ExMachina]

Mine is doing just the opposite. Sometimes it pierces the primers.

have you checked the headspace?

if it's a new gun s&w will make it right, no questions asked.