A little while ago I bought a Wiley Clapp GP100 3 inch .357 magnum. Took it to the range and ran 100 PMC .38 Specials, and 50 PMC .357 magnums through it, and it worked perfectly.

Bought one of the spring, and polishing kits, from Mcarbo, and installed it.

Thursday I took it to the range to try it out. 50 rounds of .38 special worked perfectly. After 21 rounds of the .357 I had 4 misfires. The primers were dented, but not as deep as the ones that went bang.

When I got home I installed the original hammer spring. It will be a couple weeks until I can try it out, but I'm confident that will take care of the problem. But I'm puzzled about the light strikes. Seems like it should be good, or not good. Why intermittent.

quote:

Originally posted by Muddflap:
A little while ago I bought a Wiley Clapp GP100 3 inch .357 magnum. Took it to the range and ran 100 PMC .38 Specials, and 50 PMC .357 magnums through it, and it worked perfectly.

Bought one of the spring, and polishing kits, from Mcarbo, and installed it.

Thursday I took it to the range to try it out. 50 rounds of .38 special worked perfectly. After 21 rounds of the .357 I had 4 misfires. The primers were dented, but not as deep as the ones that went bang.

When I got home I installed the original hammer spring. It will be a couple weeks until I can try it out, but I'm confident that will take care of the problem. But I'm puzzled about the light strikes. Seems like it should be good, or not good. Why intermittent.

variations in primer seating depth, variations in primer pocket, variations in primer cup or anvil, variations in cartridge headspace, friction in the hammer travel or pivot surfaces

It could just be that the spring is right on the edge between adequate and inadequate, and that it’s highlighting the slight variations in primer hardness.

It could also slightly be shifting around the strut under recoil. Did you notice anything unusual about the assembled components when using factory vs Mcarbo?

^^^ And this is why gun makers choose the weight of springs that they do - to work with all kinds of ammunition. The small dimensional or other variations can't always be seen with the naked eye.

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This message has been edited. Last edited by: egregore,

Sometimes there can be light strikes with double-action, but they go off when fired single action. This is because the hammer stroke is slightly shorter in DA than SA, and a cocked hammer has more potential energy.

As I understand it, the revolver had light strikes with the after market spring in it, but worked with the factory spring. Not a Ruger CS problem.

Deleted as not adding to the discussion.

This message has been edited. Last edited by: egregore,

Ok, I can understand some of those things making a difference.

MacGyver, and Fredward, I didn't notice anything about the Mcarbo parts that might be a problem. They seemed to be good quality. Actually, there were very few parts. There was a trigger return spring, that I couldn't use because it was too small, a hammer spring, some trigger shims, and some hammer shims. I didn't use any of the shims because they weren't needed. There must be some differences between a standard GP100, and the Wiley Clapp model. Most of the work was done with a dremel, and some Flitz. They put out a good YouTube video showing parts that could be improved by polishing, and I didn't do much of that because the parts looked pretty good from the factory.

Like I said originally, I know what caused the problem, and it has nothing to do with Ruger. I have no doubt that with the original hammer spring the gun will be back to 100%. I was just curious about the problem being intermittent, and why the .38 special worked, and the .357 had a problem.

Every load and cartridge can be very slightly different, that’s the issue. One can work around it some, only certain ammo, whatever.

Once someone does work, or has aftermarket parts installed, all bets are off.

I’ve done similar, lightened up trigger springs on a revolver. I have also gotten to light primer strikes. When that is the case, I’ve adjusted things back towards factory specs.

Another issue, the 357 rounds may have slightly harder primer cups.

I tried a lighter hammer spring in my GP100, had the same issue. OG spring with many rounds fired, made for a great trigger. Primer seating depth is when it stops going in, so thst is hard to mess up. If it is a slight high primer a second hit usually fires it. Head space on a rimmed cartridge? lol!

It sounds like it was heat induced. Is everything lubricated properly?

I suppose that's possible Jimmy. I did run 100 rounds of .38 through it first. But bottom line, I think it was me changing the spring that caused the problem. I suppose just to test that theory, since I replaced the factory spring, when I go to the range I could run a bunch of .38 through it first. But honestly I think the problem was owner induced.

I lost track of where I was going when I posted this.
My first trip to the range I shot 100 rounds of .38, and 50 rounds of .357.

My second trip, several weeks later, I only shot 50 rounds of .38, and 21 rounds of .357.

This message has been edited. Last edited by: Muddflap,

On the second run were the .357 ammo the same brand & lot as the first run?

What were the brand and load of ammo used?

As stated, when everything about the gun is the same and light strikes occur with one load but not the other, the only reason is differences between the two types of ammunition, and specifically their primers. In addition to possible differences in the primer cups in terms of hardness, seating, etc., the anvils could be different as well as the priming compound. Some compounds are more sensitive than others.

Having light strikes when the hammer force is marginal is common. Years ago when my handguns of choice were SIG Classic line pistols I experimented with different mainsprings and light strikes would occur when they became less powerful enough.

Although I’m not certain, I believe that the depth of the firing pin impact is partially due to the setback of the cartridge when it’s fired. I.e., the depth difference between cartridges that fire and don’t is partially due to the firing forces.

And FWIW, many years ago when precision revolver shooting was much more popular than today, it was reported that more powerful hammer strikes were not only more reliable for primer ignition, but contributed to greater shot to shot consistency and precision. That’s probably of no concern to most revolver shooters today, but an interesting issue (to me, anyway).

quote:

Originally posted by gjgalligan:
On the second run were the .357 ammo the same brand & lot as the first run?

Yes

quote:

Originally posted by DanH:
What were the brand and load of ammo used?

Brand was PMC
.38 was 132 grain
.357 was 158 grain

There's a gremlin in the doohickey.

quote:

Originally posted by parabellum:
There's a gremlin in the doohickey.

There's an answer I can understand.