Justin M Posted July 18, 2018 Share Posted July 18, 2018 As far as I can tell, there are a couple of implementations of the "crane lock" or "ball detent" for S&W. 1. "Traditional" which puts a ball detent on the top of the yoke/crane and a matching recess on the bottom of the frame directly under barrel. 2. "New" which puts a cartridge-style ball dent on the front of the yoke/crane and a matching recess (v-shaped) on the back of the barrel or barrel shroud. 3. "That one I saw a picture of once" where the ball detent is forward facing, but attached to a boss in the frame (a boss which doesn't seem to exist in other frames) and a matching detent in a recess (again, doesn't exist in other frames) immediately behind the forward edge of the yoke/crane. I've seen pictures of this on S&W 69s. I've never seen it in person. S&W 69s that I've seen in person have the "New" style detent. Generally speaking, the "New" and the "That one I saw a picture of once" methods delete the forward locking bolt usually found in the underlug that operates on/with the ejector rod. With the "Traditional style, the locking bolt that works in conjuction with the ejector rod remains in place (at least from what I've seen). This might seem like blasphemy, but I have to ask... Why do these detents exists? I understand that the common argument is that as the hand pushes the ratchet, the cylinder and yoke might get pushed out to the left. I hate to say it, but I want to call bulls#!t on this. The cylinder is indexed to the frame right where the hand is (by that spring-loaded plunger widget) when the cylinder is carrying up. The cylinder remains indexed when firing, but now also has the cylinder stop holding stuff aligned as well. There is also the bottom "axle" of the yoke/crane that is in the frame keeping things aligned as well. Why do these detents exist? Are they voodoo left over from a simpler time when we were all scared of the sun and only came out our caves to shoot PPC? Is the front locking bolt (that acts on the ejector rod) a vestigial tail from the Triple Lock days? (Please understand I'm trying to understand the mechanics here and not trying to criticize or otherwise insult anyone) Link to comment Share on other sites More sharing options...
MWP Posted July 18, 2018 Share Posted July 18, 2018 I agreed with almost everything you just said, until I tested it myself. I have several 929s with aftermarket barrels, so naturally there is no longer a detent active on the front of the yoke. Both my steel challenge guns and ICORE open gun were without any form of other lockup for 2 seasons, and everything seemed just fine. They were run fast, and accurately and held to factory barrels standards seemingly fine. If you paid special attention to the front of the yoke, where it meets the frame a noticeable gap was there, compared to the factory barrel and detent fit. It also could move a little compared to a factory lock up. This made me call several builders, PPC and others, and ask these specific questions. The answer I received was that it makes the gun more consistent, more repeatable, which means more accurate. I added detents and retested. Not only did my poi shift enough to make me move the sight, the guns grouped better. I've also removed the front ejector lockup from other guns and added the top yoke detent. That makes for a more consistent trigger pull across all chambers, presumably because the rods are slightly bent. Link to comment Share on other sites More sharing options...
Toolguy Posted July 18, 2018 Share Posted July 18, 2018 MWP pretty much explains it. If you watch the front of the crane on a gun without a detent, you can usually see the crane going slightly to the left as the trigger is pulled. Link to comment Share on other sites More sharing options...
Justin M Posted July 18, 2018 Author Share Posted July 18, 2018 Gentlemen, this is incredible! Thanks so much for the information. I was just getting ready to rig up a dial indicator and try to quantify some of this. I might make a jig to drill out the yoke/crane for the forward facing cartridge-style detent. I'm not sure I can notch the barrel w/o pulling it though. I'm certainly giving it way more consideration now, though, after reading your responses. Is it fair to say, then, that either style of detent (forward facing or traditional) is sufficient and provides similar results? Link to comment Share on other sites More sharing options...
alecmc Posted July 18, 2018 Share Posted July 18, 2018 the power custom ball detent works great no need to pull the barrel - notch it at the frame or get super fancy and put one to hold the cylinder open : Link to comment Share on other sites More sharing options...
MWP Posted July 18, 2018 Share Posted July 18, 2018 19 minutes ago, Justin M said: Is it fair to say, then, that either style of detent (forward facing or traditional) is sufficient and provides similar results? As far as I can tell, yes. On factory 929 and 627Pc barrels, I didn't change anything. On the ones I did, I've done singles and doubles like Alec showed above, but I haven't really seen a benefit of more than 1. Link to comment Share on other sites More sharing options...
Justin M Posted July 18, 2018 Author Share Posted July 18, 2018 Once a traditional detent is added (like alecmc suggests), the front spring-loading locking pin (that acts on the end of the ejector) can be removed then? Thanks again! Link to comment Share on other sites More sharing options...
alecmc Posted July 18, 2018 Share Posted July 18, 2018 (edited) 42 minutes ago, Justin M said: Once a traditional detent is added (like alecmc suggests), the front spring-loading locking pin (that acts on the end of the ejector) can be removed then? Thanks again! Yes, you can remove the lock in pin in the barrel shroud. This also aids in performance, if you're ejector rod gets slightly bent out of shape you wont feel it in the trigger like you usually would when the rod locks up on the shroud lock like factory. Edited July 18, 2018 by alecmc Link to comment Share on other sites More sharing options...
alecmc Posted July 18, 2018 Share Posted July 18, 2018 54 minutes ago, MWP said: On the ones I did, I've done singles and doubles like Alec showed above, but I haven't really seen a benefit of more than 1. This - I'd stick with just one - When I added two to my open gun it was just an experiment ( and I thought it looked cool ) . No added benefit over having a single detent. Link to comment Share on other sites More sharing options...
Toolguy Posted July 18, 2018 Share Posted July 18, 2018 The trick of a good lockup is in getting the detent matched to the ball. If the detent is too big, the crane can still have side play before the ball contacts the side of the detent. If it's too small or off location, the ball is still mostly compressed in it's hole and takes very little to pop it open. Ideally, the ball will be extended most of the way, while contacting the side of the detent. Link to comment Share on other sites More sharing options...
Justin M Posted July 19, 2018 Author Share Posted July 19, 2018 A couple more questions before I set off to work... 1. Has anyone considered using a threaded cartridge-style spring plunger in the "tradional" orientation? Assuming that the most common size is #30 for the drill (Power Custom), a #8 would be an easy fit, although a #10 should be fine as well and offers a bit more nose force. There would be the issue of ensuring the location of the detent allows for a slightly deeper hole. From what I can determine, and there are enough assumptions being made that this is mostly a wild-ass guess, the press fit cartridge-style plunger used in the PC forward facing detents has about 5lbs of nose force give or take. Something like this: https://www.mcmaster.com/#3408a91/=1ds5xy3 2. Again, working from assumptions, the PC style forward-facing detent would seem to be, intuitively, far more effective than the traditional style. It likely exerts far more force on the yoke and this force is (sort of) along the axis of the barrel/cylinder. Is there any observed benefit to this? I'll be honest, at this point, I'm strongly considering the PC style detent. A jig for drilling the crane would be trivial. A jog for notching the barrel while it is still install would not be, but it would possible, I believe. Removing the barrel is always an option, but I'd prefer to come up with a quick bench method. Link to comment Share on other sites More sharing options...
Toolguy Posted July 19, 2018 Share Posted July 19, 2018 I think the only advantage to the cartridge style detent is that it's a self contained unit and easier to install. There is no room for that in the vertical orientation. You have to locate the hole pretty accurately to keep from breaking into the hole on the crane for the ejector rod or breaking out on the outside of the crane. The crane below the ejector rod has more meat to work with so you can put a cartridge style plunger facing forward. The vertical style holds securely if done right. Link to comment Share on other sites More sharing options...
alecmc Posted July 19, 2018 Share Posted July 19, 2018 Keep in mind if you decide to stick with the forward facing type - you limit yourself to barrel modifications , example - if you ever decide to go with an aftermarket open barrel, or modify a stock barrel - like shaving off the underlug. Not that this is giant deal - just throwing it out there. Link to comment Share on other sites More sharing options...
Justin M Posted July 19, 2018 Author Share Posted July 19, 2018 11 minutes ago, alecmc said: Keep in mind if you decide to stick with the forward facing type - you limit yourself to barrel modifications , example - if you ever decide to go with an aftermarket open barrel, or modify a stock barrel - like shaving off the underlug. Not that this is giant deal - just throwing it out there. This! This is an interesting observation. Thanks for the insight. Ordering the Power Custom kit and calling it a day. Thanks. Link to comment Share on other sites More sharing options...
alecmc Posted July 19, 2018 Share Posted July 19, 2018 2 hours ago, Justin M said: This! This is an interesting observation. Thanks for the insight. Ordering the Power Custom kit and calling it a day. Thanks. Good to hear, I personally wouldnt put in the effort trying to reinvent the wheel on this one. The power custom ones like I showed about are pretty tried and true and work very well. Additionally - Penciled barrels are pretty awesome to have too! Link to comment Share on other sites More sharing options...
MWP Posted July 19, 2018 Share Posted July 19, 2018 2 hours ago, Justin M said: This! This is an interesting observation. Thanks for the insight. Ordering the Power Custom kit and calling it a day. Thanks. If you're using a drill press, you don't need the jig that holds the crane, assuming you have something to hold it with on your press. Just the balls, springs and punch is all I use. And it's a 1/8th drill bit, nothing exciting there. Link to comment Share on other sites More sharing options...
Powder Finger Posted July 19, 2018 Share Posted July 19, 2018 this was a set up by Jerry Keefer for the detent part of it. Link to comment Share on other sites More sharing options...
alecmc Posted July 20, 2018 Share Posted July 20, 2018 Link to comment Share on other sites More sharing options...
PatJones Posted July 20, 2018 Share Posted July 20, 2018 Additionally - Penciled barrels are pretty awesome to have too! The pencil barrels kinda have a weird Colt thing going on. Link to comment Share on other sites More sharing options...
swordfish Posted July 24, 2018 Share Posted July 24, 2018 The ball end bit is actually pretty terrible for the detent side. Too much of an angle that doesn't require a lot of pressure to pop the cylinder out. Better is a cutoff wheel or something where you can get a totally flat/perpendicular edge, then round as much as necessary so it's not too tight. I used a ball bit on my first go and it just seems loose. Better than nothing, but I was told after the fact by my revolversmith/mentor that there is a better way. Link to comment Share on other sites More sharing options...
Gregg K Posted July 25, 2018 Share Posted July 25, 2018 On 7/24/2018 at 9:12 AM, swordfish said: The ball end bit is actually pretty terrible for the detent side. Too much of an angle that doesn't require a lot of pressure to pop the cylinder out. Better is a cutoff wheel or something where you can get a totally flat/perpendicular edge, then round as much as necessary so it's not too tight. I used a ball bit on my first go and it just seems loose. Better than nothing, but I was told after the fact by my revolversmith/mentor that there is a better way. Hmm, a picture is worth a thousand words. Link to comment Share on other sites More sharing options...
Justin M Posted July 26, 2018 Author Share Posted July 26, 2018 That seems to be what S&W has done as well. With the forward-facing, cartridge style balls detents the ball/plunger lines up with a "v-groove" and is at "rest" (ie: yoke closed and cylinder in battery or whatever you call it when you're using a cowboy gun) but is a little bit off the deepest part of the "v" so the ball/plunger is acting on the yoke front to back and exerting pressure inward. There's some discussion on it here: http://smith-wessonforum.com/s-w-revolvers-1980-present/375590-fyi-model-69-66-8-ball-detent-design.html Link to comment Share on other sites More sharing options...
swordfish Posted July 26, 2018 Share Posted July 26, 2018 12 hours ago, Gregg K said: Hmm, a picture is worth a thousand words. Link to comment Share on other sites More sharing options...
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