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SP-101 timing

2K views 9 replies 3 participants last post by  Varmiter 
#1 ·
Two of the 5 cylinders on my SP-101 aren't fully locked before the hammer falls. They are only off by just a hair. Is this dangerous? I have done an IBOK trigger job, and read that an out-of-spec pawl could be the cause. If that was the case for me, wouldn't all 5 spots be off? All I did to the pawl was polish the top and sides, and the little tip of the boot.

If it's a problem with the cylinder ratchet, I couldn't see a part number for it in the IBOK. Is that something Ruger or Brownells sells?

Is there anything else I can try to attempt to correct the timing problem?
 
#2 ·
Does this happen in both SA or DA or both?

In any event, don’t fire the gun until you find the problem.

While there could be a problem with the ratchet/pawl, I suspect the hammer is falling early on all chambers, but three of them are locked up.

On mine, when all five chambers first lock, the hammer travels about another .025 inch before it falls in DA.

Chris
 
#3 ·
dBA, The ratchets are seldom perfect where carry-up timing is exactly the same on all chambers. That's not your problem ... just one of the side issues. I betting you took a bit too much off the tip of the pawl. This can be a critical part where a few thousandths makes the difference between working and not working.

Check your endshake. If it is too generous, you'll get the same symptoms.
 
#4 ·
If the endshake is too generous, will a new pawl fix this? I really don't think I took too much (if any) off the pawl. Just a polishing.

One other thing, the cylinder does end up locked after the hammer falls (or perhaps it shakes itself into lockup as the hammer falls). Is this still a dangerous condition?

Thanks for all your help
 
#5 ·
dBA, SP-101s almost always time up a bit early. If they don't, there's always a reason. If you have excessive endshake where the cylinder can move too far forward, then yes, it will affect carry up. A new pawl will likely fix the problem. The pawl could have been a tad short from the factory and just dressing it a little might put it under minimums.

As Varmiter suggests, your hammer dog may be releasing the hammer too soon but I really doubt it. The SP has a DA sear so if it doesn't transfer properly, it will try to pull the trigger forward when the hammer releases.

The gun is not safe to operate in this condition. If the cylinder fails to lock up but there is enough primer showing to get hit by the firing pin, the bullet will bounce off the forcing cone and do permanent damage ... could even cause an injury. Pawls are much easier to replace than eyeballs or hands.
 
#7 ·
Iowegan is probably right, but the hammer falling early is still a valid question.

Does this happen in DA, or SA or both? The answer will point to the problem.

Internet diagnosis is difficult as it is, but when questions are asked, answers are needed. Otherwise, it is just guesswork.

Chris
 
#10 ·
Well, in SA, it isn’t falling early. The fact that the cylinder locks up in SA narrows the search a bit. Well, not quite true, but it confirms the problem could be in one of two places.

I think Iowegan is right in that you probably took a bit too much off the pawl. That is assuming you didn’t touch the hammer dog.

Again, don’t fire the gun until the problem is fixed.

Many people, incorrectly assume “Polishing” is determined by the eye. Mechanically, two rough surfaces, which are flat at the top, can easily work with another rough surface whose grain is also flat at the top but running at a completely different angle. The valleys in these surfaces contain the lubricant for smooth operation. A mirror shine is not necessarily desirable.

I suggest you order a new pawl.

Chris
 
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