Ruger OM Vaquero malfunction

[Coyote3855]

After 10 years and thousands of rounds, one of my Vaqueros went south this weekend. I shot a CAS match Saturday with no problems. After a few cycles of dry fire that evening, the hammer would not cock. I fiddled a bit and it worked for about 15-20 cycles, then locked up again.

Symptom: The hammer will come back to the point where the cylinder should start to turn, then the hammer cannot be pulled to full cock and the cylinder will not turn. The gun locks up with the cylinder in or out. Lowering the hammer a few times will usually allow the hammer to cock.

Attempted fixes: Checked the cylinder base pin. It was intact (pin in place at the hammer end) and fully seated. Checked to see if transfer bar was hanging up on the firing pin. Lock up occurs when the transfer bar is still slightly below the firing pin. Disassembled the entire gun, used Gun Scrubber to clean accumulated crud, lightly oiled, and reassembled. Would do the 15-20 cycles and lock up. Disassembled offending gun and its mate to compare parts. Couldn’t see anything broken or worn or different from the Vaquero that works.

Options: I am reluctant to send the gun to Ruger. Both guns have action jobs and matching two- pound triggers. Ruger will put it back to spec. I have an OMV Sheriff’s model. Would it be worth a shot to put those parts in the bad gun?

Got some responses on the SASS wire suggesting it may be a problem with the hammer plunger, cross pin, and spring. I'll check that out, I didn't even know the part was there.

Ideas?

Thanks,

Coyote3855

 

[Jim K]

The hammer plunger is the little plunger that cams the cylinder latch (cylinder stop) down so the cylinder can turn. But it is not pressed back when cocking the gun, so I think that is not the problem.

Try this check: Remove the cylinder, then try to cock the hammer. Watch the cylinder stop at the bottom of the cylinder window. If it does not retract down into the frame, your problem is either in the cylinder stop, or in the cylinder stop plunger/spring. Wear is a possibility, as is a problem with the hammer plunger, but I suspect dirt or mis-assembly in the cylinder stop or cylinder stop plunger area.

If you need parts, Gun Parts Corp. (www.gunpartscorp.com) has them so you should be able to avoid returning the gun to Ruger.

Jim

 

[gb6491]

As Jim mentions, Gun Parts Corp is a good source for parts as is Brownells. I've also had good dealings with ebay seller "Miga Gun Parts" in regards to Ruger parts.
If it turns out to be the plunger, I have made several of them out of dental burrs and old drill bits to adjust the timing of the cylinder stop on my Bisley Vaquero. It's not that difficult a part to make.
The plunger, pin and spring:

The original plunger , a handmade one and one in progress:

Original:

Adjusted:

Regards,
Greg

 

[Coyote3855]

Jim and gb6491,

Thanks for the info and especially the excellent pictures. Look like your handmade plunger is longer than the original part? Was that to eliminate the famous Ruger drag line on the cylinder? How does it affect the timing?

Coyote

 

[gb6491]

Hi Coyote3855,
Yes, the handmade one is a little longer. Timing wise, the cylinder stop (Ruger calls it a latch) now comes up just before the start of the scallop on each chamber; eliminating most of the drag line.
There is a limit to how long the plunger can be made before you start having problems with cocking or the hammer dropping. If you set it up below that length you should have no problems. Wear from that point will just cause the stop to come up earlier. I have an oversize stop/latch that I'll try (someday) to mate with a plunger to get the timing to the point that the stop comes up in the end
of the scallop.

Regards,
Greg

 

[Coyote3855]

Greg and Jim, Thanks again for your assistance. The hammer plunger spring was broken. I replaced it with the spring from the Sheriff's Model and just now ordered new parts from Ruger. Nice pic of your Bisley, no annoying line!

Coyote3855