M66 bolt (or cylinder stop) engagement

[Dave Sample]

These double action revolvers are pretty good shooters for the most part. I always think of the intended purpose for owning the handgun when I think of how tight they are fitted. I am still in the business of tuning SA revolvers and I do work on the bolt to bring it up into the full depth of the notch in the cylinder and also to come up at the right time. Most double action's pop the bolt up right after they start the cylinder rotation and let the bolt ride the cylinder all the way around. Hence the shiny ring on the cylinder. If we see this on a SA we know the gun has been mis-handled by dropping the hammer from 1/2 cock to lower it. We always try the bolt in the cylinder notches to see if it is too thin and then replace it with a new one if that is the case. The bolt is what holds the cylinder in postion while the round is fired and it should be tight in a SA with no rotation. The bolt has to be up in the notch and fill the notch for the maximum accuracy of the fired round. DA's are not as easy to achieve this with and the bolts are flimsy compared to a SA. I never bothered working on DA bolts because the results were not there. I also would guess that a new cylinder is a cheaper way to fix notches that have been abused rather than trying to repair one.

 

[bountyhunter]

Did the homework for you

quote:
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Can you set up a M1911 really tight? Sure.
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That's a separate myth: that a 1911 has to rattle to be "reliable". Read the Kuhnhausen manual on the correct fit for a 1911 (barrel/slide/frame) and you will find they say it is when the barrel in lockup rests with the lower lugs on the slide stop cross pin (NO PLAY) and the upper lugs inserted into the slide cuts with the barrel snug against the slide.

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I've just taken a good deal of time I'd rather have spent doing something else going through Kuhnhausen's book.

Well, I don't want to be responsible for people having to waste time reading reference manuals so I did the work. Regarding the above statement about the way a 1911 is supposed to be fitted:

The US M1911/M1911A1 Pistols
A Shop Manual
By Jerry Kuhnahausen

Page 131 (center page)

Historical Note

"....Before barrels with oversized lugs were manufactured, bottom lugs were built up by welding and then re-cut to vertical dimensions and contour that would cam the barrel over the top of the slide stop crosspin and into the 100% vertical lug engaged position as the barrel linked upward into battery. When bottom lug surfaces ARE CORRECTLY CUT TO A ZERO CLEARANCE BOTTOM LUG-SLIDE STOP CROSSPIN FIT on a correctly aligned barrel, a triangular, mechanically positive barrel support condition is achieved wherein the bottom barrel lugs resting on the slide stop crosspin form the mechanical base of the support triangle and top barrel lug slot-slide contact at the 12-oclock position forms the apex (of the triangle)."

I am not saying ALL 1911's are fitted this way. In fact, no mass-made gun is fitted this way. But, it is still the correct fit. And if you ever wondered why a Wilson, Valtro, or STI costs twice what a Kimber does: this is one place the money goes.

 

[bountyhunter]

Here is what I said was in Kuhnhausen:


quote:
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As for "fits" that have no play: read the Kuhnhausen spec on what the proper clearance is for front-rear cylinder play (end shake): it is ZERO to one thousandth of an inch (0 - 0.001").
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And here is the referencwe I quoted when I said that:

The S&W Revolver
A Shop Manual

By Jerry Kuhnhausen

Page 26, RHS of page half way down.

"4. Install the cylinder again and recheck for end shake. If the bearing runs tight, and it is the smallest (shim), trim the yoke face very carefully until approximately .001" end shake clearance remains."

Got it?

End shake shall not exceed .001", which means the spec is 0.000 - 0.001".

 

[bountyhunter]

Most double action's pop the bolt up right after they start the cylinder rotation and let the bolt ride the cylinder all the way around.

SW's are designed to have the stop come up a bit past halfway between notches.

Kuhnhausen, page 58:

"2.....Generally, the stop will pop up slightly past the halfway mark as the cyclinder rotates."



That is why the drag line on the cylinder is always heavier in the second half of the distance between cylinder notches.

 

[Dave Sample]

If that is the case, then why is there any drag line of any dimension all the way around on them? I suggest that those of you who own these guns take a look at what happens when the cylinder starts around. All you have to do is hold the gun in a good light, and watch the bolt as you start to rotate the cylinder. Some pop up sooner than others, but they all pop up before they hit the notch. I love Jerry's books, but I rarely read them and only use them for dimensions of parts. Factory guns are built to sell. If they are built tight on a Wednesday, that is a bonus.

 

[bountyhunter]

If that is the case, then why is there any drag line of any dimension all the way around on them? I suggest that those of you who own these guns take a look at what happens when the cylinder starts around.

If you know anybody in a "collectable" shop, they will know the answer immediately. When you open and then close the cylinder, people generally pay no attention to where the cylinder closes and then you have to turn the cylinder by hand to the next notch before the action is set again. That is where the fine line in the first 1/3 of the cylinder comes from. In collectable shops where they sell "like new" model 27 blue guns (for upwards of $800 out here) they will never let you close the cylinder. they will do it with the cylinder indexed so that it will not drag the "line".

 

[bountyhunter]

Some pop up sooner than others, but they all pop up before they hit the notch.

That is true, but the "60% point" between slots is WAY before the notch or even the "ramp" portion of the cut. No disagreement that the stop pops up well before the cut. If you see a stop popping up significantly before about 1/2 way, it means the trigger nose or the stop has worn because it is releasing too soon. Or, a new stop was installed and fitted wrong by removing too much material. The front edge that mates with the trigger is fitted by filing until the stop drops (at it's lowest point) about halfway between the top frame surface and the inner frame surface. If it goes too low, it can snag on the lower edge of the cut. Not low enough, and it doesn't release properly.

 

[bountyhunter]

I suggest that those of you who own these guns take a look at what happens when the cylinder starts around. All you have to do is hold the gun in a good light, and watch the bolt as you start to rotate the cylinder.

Good idea. You will hear a definite "click" when the stop releases from the trigger edge and allows the stop to pop up against the cylinder. Check new guns to see where it is supposed to happen then check your guns. Wera of the stop and/or trigger edge will gradually make the stops come up a little sooner. To be safe to use, the very top of the stop should at least pull down even with the top of the frame and allow the cylinder to release well past the cut before it comes back up to make sure it won't hang up.

 

[Dave Sample]

I have two of these left and they are both Taurus'. One is a Raging Bull .454 Casull and the other an older Model 66 .357 Magnum, both in Blue Steel. The bolt on these two comes up the minute it's out of the notch and the tip of the bolt rides the cylinder all the way around. I will, of course , bow to Bountyhunters superior knowedge and experience, and just say that what I know, I know from the guns I have worked on for 20 some years. Single Action Rugers do the same thing and I have had many complaints about this cylinder ringing, but I just tell them that it's the nature of the beast and the way they are designed. I have never concerened myself with the sloppy fit of DA Bolts as the slot they come out of is too large to keep it rock solid. This is not true of good well built SA Revolvers. The slot is offset, but tight and the bolt fits the notch tight so they are a lot better than the DA's. I think SA's are safer ,too, because you have to pull the hammer back to fire them instead of just pulling the trigger.

 

[bountyhunter]

I don't smith Rugers or Tauri so I don't know how they time. I'll guarantee you that a properly fitted SW will not pop the stop up until the cylinder has rotated about half way between cuts. It's easy to see this: turn the gun upside down so you can loog straight down on the cylinder as you slowly draw the hammer back (or pull the trigger). Listen for the click and see where the cyl cuts are with respect to the frame. You will probably see a cut on either side, close to being centered around the frame.

As to the primary source of the fine ring on the front half of SW's: it is from closing the cylinder and then turning it to lock up or more commonly, "freewheeling" to check how smoothly it turns. You pull the trigger just enough to lower the stop then turn the cylinder. Then when you release the trigger, you have to turn the cylinder by hand until it hits the next notch. The stop is a hardened piece held against the cylinder by a spring and it does not take much dragging to make the fine line.

 

[bountyhunter]

I have never concerened myself with the sloppy fit of DA Bolts as the slot they come out of is too large to keep it rock solid. This is not true of good well built SA Revolvers.

Also not true of a properly fitted SW DA wheelgun. I currently own six of them. When new, that fit should be pretty tight. The edge of the slot peens over with use and it does get sloppy with time.