light strikes M28-2 (resolution: 11/17/10)

[loutent]

I was enjoying my HP yesterday at the range - shot about 20 or so 38's without a hitch, then decided to run some 357's through it. Had two light strikes FTF in about 12 rounds. Went back to the 38's and finished the entire box of 50 without a problem. Both were Rem UMC target ammo - nothing special, no reloads as I don't do that (yet).

After some research here, I saw a couple suggestions:

1. back off the strain screw a little (half-turn)
2. flatten the hammer spring a little (with a plastic mallet)
3. don't touch anything - get a new spring

What are the current best thoughts?

See last post for wrap-up

 

[USBP SW]

If the strain screw has been "backed off", I would tighten it. That should fix the problem. I have seen people attempt to reduce the spring tension by grinding the sides of the mainspring, which necessitates replacement of the mainspring to correct. Some folks grind the strain screw, which requires replacement of the strain screw to correct. I am not a proponent of any reduction in mainspring tension, I prefer the extra margin to ensure positive ignition. Just my opinion.

Good luck,
Steve

 

[Stillwater788]

Is it the ammo or the gun? If your HP has run fine for 100's/ 1000's of rounds and it was just this one box of .357s - suspect the ammo. Try running it through a know good revo and see if you get FTFs. If you suspect the gun - make sure the strain screw is fully tightened. Tighter = more spring tention and more force to the primer blow from the hammer. It may be that over time the screw has backed itself out enough to not ignite the primers in the .357s but the .38s work ok due to tolerance differences in the ammo. Let us know what you find.

 

[Nightowl]

It could be a little endshake, as well. Sometimes it does not take much to move the cartridge farther from the firing pin. As stated above, it could be the ammunition has less rim thickness and maybe a little endshake would act in combination to have misfires. The strain screw and mainspring items talked about are also possibilities.

 

[stevieboy]

First thing I'd do is check that strain spring. They can back out with time and even 1/2 - 3/4 turn will sometimes be enough to produce light strikes. Did you look at the impression that the firing pin made on the back of the "dud" rounds?

By coincidence I was at the range a couple of days ago with my 28-2 and I fired off about 100 rounds of factory .357 (Magtech). I got what I thought was a light strike and a FTF on about the 4th round I fired. I recycled the cylinder and tried again, still no go. I checked the round, there was a deep impression in the primer, certainly as deep as the ones left in all of my fired rounds. I kept shooting, shot another 95 or so rounds without a problem. My conclusion was that I simply had a round with a bad primer. That happens, even with factory ammo.

 

[loutent]

First thing I'd do is check that strain spring. They can back out with time and even 1/2 - 3/4 turn will sometimes be enough to produce light strikes. Did you look at the impression that the firing pin made on the back of the "dud" rounds?

I saved the duds and just took a quick photo of the FTF ones (on right) compared to the normal ones on left:

 

[Buford57]

Those are definitely light strikes and I wouldn't blame the ammo. Backing the strain screw out farther will not help, but make things worse. As others have suggested, try to tighten the screw first before you start replacing parts. Improperly modified parts (strain screw or mainspring) are the next easiest to address (neither is hard to replace) and end shake is also a possibility, although I would be inclined to save that for last.

 

[srgvaz]

Have you ever cleaned the internals of you HP? If not start there make sure the main spring is flat-ish, and the strain screw is tight.

 

[stantheman86]

If the mainspring is stock, and the strain screw un-shortened, endshake would have to be severe. I have a 28-2 that I got as a "project", it had so much endshake the cylinder rattled back and forth in full lock up. It still touched off some cheap Armscor .38 being that loose, and even then after shooting I realized the last owner had backed the strain screw out..... then the cylinder required 4 .002 endshake bearings to get it tight, and even still it has some endshake.

I would say the ammo has hard primers, if it was the gun all of the ammo would show light strikes. The hits on the rounds that fired look pretty deep.

 

[Nightowl]

I am concerned that the primer indentions are not centered. It could be a timing issue where the cylinder stop does not stop the cylinder in time and it turns a little past center. A friend of mine had a problem like that. The Smith term for it is "throw by".

 

[cmj8591]

The order of diagnosing your problem is this:
1. Tighten the strain screw all of the way if it is loose.
If that doesn't fix the problem then:
2. Replace the strain screw.
If that doesn't work:
3. Replace the main spring.
If it were my gun I would replace the screw and the spring.
I don't think this is a head space problem because if it was, you would be getting lots of lead and residue shooting out of the gap between the cylinder face and the barrel throat. But try tightening the strain screw first as many table top gunsmiths use the loosening the strain screw method to lighten the double action pull.

Good luck

 

[ken158]

The strain screw is not an adjustment and is designed to be tight. Put it where it belongs and shoot again.

 

[loutent]

Thanks everyone for all the suggestions. I removed the grips and found the strain screw to be about 1.25 revolutions backed off from tight - maybe it just worked loose on its own. Tightened it up and I will test it out next time at the range and report back.

Now I'm kind of worried about the strikes not being exactly centered - will keep an eye on that too.

Thanks again!

 

[cmj8591]

That should correct your problem. Don't worry about the off center strikes. That shouldn't cause any trouble.

 

[loutent]

Resolution!

So after a month, I finally got my 28-2 back to the range today - usually we shoot every 2 weeks, but last time I grabbed the 27 instead (it was early morning.) Anyway, I put a couple dozen 357 through the 28 today and had absolutely no issues with light strikes - and it was from the exact same box of ammo as before.

Jeez I love that revolver - what a pleasure to shoot - I might like it more than my 27 but of course it's not as pretty

Thanks all - this is a great forum!

 

[Black Knight]

The 27 is like a Lincoln Towncar and the 28 a Ford or Chevy truck. The 27 is for looks and status while the 28 is for getting the job done with no extra bells and whistles. The 28-2 is my first S&W. After 30 years I still have and enjoy it. Enjoy both, you have the best of both worlds.