rhyrlik Posted May 12, 2008 Share Posted May 12, 2008 Hi, I need some input from you experts: I have a bulge in my barrel right at the shoulder. I can feel it when I run a tight patch through. I feel resistance all the way through the bore, then no resistance for a quarter inch, then some resistance until the patch is out of the forcing cone. I wanna pull the barrel off my 625 and set the shoulder back by about .002" which will allow the barrel to go back on with less torque and hopefully eliminate the bulge. I noticed Brownells sells a jig with a cutter that allows you to set the shoulder back without a lathe. Has anyone used this thing? Any issues? Link to comment Share on other sites More sharing options...
slflr Posted May 12, 2008 Share Posted May 12, 2008 Hi, I need some input from you experts:I have a bulge in my barrel right at the shoulder. I can feel it when I run a tight patch through. I feel resistance all the way through the bore, then no resistance for a quarter inch, then some resistance until the patch is out of the forcing cone. I wanna pull the barrel off my 625 and set the shoulder back by about .002" which will allow the barrel to go back on with less torque and hopefully eliminate the bulge. I noticed Brownells sells a jig with a cutter that allows you to set the shoulder back without a lathe. Has anyone used this thing? Any issues? Ralph, The hole in the tool bit does not allow enough adjustment for it to reach the shoulder of the barrel. It must be elongated to provide that adjustment. If you wish, I will loan you my fixture. PM me with your address and I will mail it to you. Get it back to me when you are done. Bob Link to comment Share on other sites More sharing options...
Pin Shooter Posted May 12, 2008 Share Posted May 12, 2008 Once again.....Bob demonstrates what makes shooters such great people. Link to comment Share on other sites More sharing options...
cliffwalsh Posted May 12, 2008 Share Posted May 12, 2008 I will loan you my fixture. Don't fall for that old trick. The last thing you want to put your hands on is Bob's 'Fixture'. Link to comment Share on other sites More sharing options...
rhyrlik Posted May 12, 2008 Author Share Posted May 12, 2008 Bob, That's very kind of you. I'm not quite ready yet, but I'll PM you soon. How does that jig work? Ralph Link to comment Share on other sites More sharing options...
Patrick Sweeney Posted May 12, 2008 Share Posted May 12, 2008 Ahhh, let's back up here. You can feel a tight spot in the barrel right at the barrel/frame meeting point? Or some weird tight-loose-tight effect? Setting back the barrel isn't going to help. That tight spot is the barrel squeezed down from the torque of tightening. Set it back, torque it up and the bulge comes back. Install the barrel without torque, and how is it going to stay put? If the situation really is a problem, the only solutions I know of are either a new barrel, or fire-lapping the existing barrel. How does the gun shoot? Can you get the accuracy you need? How is the fouling? If there isn't a problem, don't go looking for solutions. Link to comment Share on other sites More sharing options...
HSMITH Posted May 12, 2008 Share Posted May 12, 2008 It is loose right at the shoulder from what I am reading. I would use the old Mark 1 Mod 0 eyeball and some good light to see what is going on. A tight spot under the threads is pretty common, and the cure is to chase the threads on both the barrel and the frame so that the barrel isn't being crushed under the threads, and make sure the frame and barrel shoulder are dead square. If it is looser right at the shoulder than it is anywhere else, well there isn't much you can do short of setting the barrel back enough to cut that loose section completely off, and that is not a practical solution. I would rebarrel it at that point. If it shoots good and presents no problems other than a funky feeling cleaning rod pass I would recommend you stop cleaning the bore, you won't feel the funky spot and all will be well with the world. If you cannot stop cleaning the bore for some reason try to ignore it. If it doesn't shoot or presents some sort of problem by all means fix it. Link to comment Share on other sites More sharing options...
rhyrlik Posted May 12, 2008 Author Share Posted May 12, 2008 It's a loose spot. You can see it when you point the muzzle at a light source and look down the forcing cone. The gun shoots poorly with ball ammo, 3-4" groups at 15 yards from a benchrest, but excellent with plated bullets- about an inch. The gun is mechanically sound with perfect timing. The only issue is that loose spot. I wanna shoot cast bullets and this may cause problems. I was also thinking about Taylor Throating it while I have the barrel off. I read the following account: http://journals.aol.com/johnstranahanb/Reb...bench-vise/1010 He got rid of the loose spot just by removing the barrel. I guess the barrel extension/shoulder joint got stretched when they overtorqued it at the factory. Link to comment Share on other sites More sharing options...
Toolguy Posted May 12, 2008 Share Posted May 12, 2008 Hi, I need some input from you experts:I have a bulge in my barrel right at the shoulder. I can feel it when I run a tight patch through. I feel resistance all the way through the bore, then no resistance for a quarter inch, then some resistance until the patch is out of the forcing cone. I wanna pull the barrel off my 625 and set the shoulder back by about .002" which will allow the barrel to go back on with less torque and hopefully eliminate the bulge. I noticed Brownells sells a jig with a cutter that allows you to set the shoulder back without a lathe. Has anyone used this thing? Any issues? The easy way to fix that is to remove the barrel, turn enough off the back shoulder of the barrel so that it will tighten up straight by hand with no wrench (usually 2 or 3 thou). Carefully take off just a little bit and try it, then a little more and try that, etc. till you arrive. Clean male and female threads with brake parts cleaner, apply red Loctite (#271) and reassemble, making sure the front sight is true vertical. It is easier to tell looking from the front sight to the back sight than from back to front. Wipe off the excess Loctite and let it cure over night. Job done. Link to comment Share on other sites More sharing options...
Carmoney Posted May 12, 2008 Share Posted May 12, 2008 Taylor Throating is simply cutting the forcing cone to a 10-degree chamfer. (11 degrees has been one of the industry standards for many years, although it doesn't have a cool-sounding name.) But getting back to the issue here......does somebody want to explain how an overtorqued barrel could create a "loose spot" or "bulge" in the bore?? That makes no sense to me at all. Link to comment Share on other sites More sharing options...
rhyrlik Posted May 12, 2008 Author Share Posted May 12, 2008 Because it would stretch the barrel extension/shoulder joint? I know it is generally accepted that overtorquing causes a constriction, but if the joint is too thin to begin with? Toolguy, I like the idea of Locktite. When you pulled the barrel, did the barrel extension spring back to eliminate the bulge, or did the bulge remain? The reason I ask is if the bulge remains, there's no point to pulling the barrel. Link to comment Share on other sites More sharing options...
Toolguy Posted May 12, 2008 Share Posted May 12, 2008 (edited) Because it would stretch the barrel extension/shoulder joint? I know it is generally accepted that overtorquing causes a constriction, but if the joint is too thin to begin with?Toolguy, I like the idea of Locktite. When you pulled the barrel, did the barrel extension spring back to eliminate the bulge, or did the bulge remain? The reason I ask is if the bulge remains, there's no point to pulling the barrel. It will if the bulge is a result of over tightening or "crush fit" as some call it. If the bulge was created by a bullet stuck in the bore with another fired behind it, you need a new barrel. Either condition can exist. If you get another barrel, fit it to tighten up by hand as described and you will have neither constriction or bulge. Both problems are caused by over tightening so both can be fixed by not over tightening. I have done many barrels this way with excellent results. Mike, if you have ever seen a piece of rod in a tensile strength test, you would notice that before it breaks the middle gets thinner equally on all sides. The same is true with a tube. When stretched, the outside diameter gets smaller and the inside diameter grows larger because the wall thickness is equally decreased on both sides at the same time. Edited May 12, 2008 by Toolguy Link to comment Share on other sites More sharing options...
Carmoney Posted May 12, 2008 Share Posted May 12, 2008 Sorry, but I'm still having a hard time imagining this could be true. Everything I've ever heard about "over-torqued" barrels on S&W revolvers (which I suspect is largely a non-issue for most practical purposes) has involved a slightly tight spot that is detectable where the barrel is screwed into the frame. For a loose spot to occur from overtorquing, wouldn't it have to be like squeezing a balloon--the place where you squeeze gets smaller in diameter, but another spot on the balloon gets bigger? Obviously, balloon physics doesn't apply here, since we're talking about rigid steel, not flexible rubber, and the interior of a cylinder that is not airtight, right? Link to comment Share on other sites More sharing options...
Round_Gun_Shooter Posted May 12, 2008 Share Posted May 12, 2008 If you need a 5" barrel I have one I could be convinced to sell. It is a take off but is in excellent condition. It sits and cries while next to the blue barrels I don't want it to make them rust. Link to comment Share on other sites More sharing options...
Toolguy Posted May 12, 2008 Share Posted May 12, 2008 Sorry, but I'm still having a hard time imagining this could be true. Everything I've ever heard about "over-torqued" barrels on S&W revolvers (which I suspect is largely a non-issue for most practical purposes) has involved a slightly tight spot that is detectable where the barrel is screwed into the frame. For a loose spot to occur from overtorquing, wouldn't it have to be like squeezing a balloon--the place where you squeeze gets smaller in diameter, but another spot on the balloon gets bigger? Obviously, balloon physics doesn't apply here, since we're talking about rigid steel, not flexible rubber, and the interior of a cylinder that is not airtight, right? On a 625 the metal is fairly thin between the end of the threads and the shoulder that goes up against the frame. Some barrels are thinner than others there. It's a case of the weakest area giving first. If it is too thin there, as RHYRLIK suggested, it can stretch, making the tube wall thinner. When it is stretched, the cross section of the tube wall develops an hourglass shape, becoming smaller on the outside and larger on the inside. If the thread relief area is thick enough, then it squeezes down the barrel diameter instead. You will never see the internal bulge on a 686 because it is plenty thick there. The 686 can be bulged by a stuck bullet, or squeezed down by over tightening. Link to comment Share on other sites More sharing options...
rhyrlik Posted May 14, 2008 Author Share Posted May 14, 2008 Brownells just told me their fixture will not remove material from the barrel rib or the underlug. It looks like I'll need a lathe after all. Maybe one of those mini lathes from Harbor Freight? Link to comment Share on other sites More sharing options...
Flexmoney Posted May 14, 2008 Share Posted May 14, 2008 Moderating note: I split the Taylor Throating talk off into it's very own thread. Let me know if I didn't get some of the post properly placed (by post number, please). Taylor Throating thread here: http://www.brianenos.com/forums/index.php?showtopic=65216 Link to comment Share on other sites More sharing options...
Flexmoney Posted May 14, 2008 Share Posted May 14, 2008 When it is stretched, the cross section of the tube wall develops an hourglass shape, becoming smaller on the outside and larger on the inside. The "hourglass" description throws me off, as I think of an hourglass as caving inward too. (and, I was thinking of the tube as a whole...makes more sense just to think on one side of the tube...the wall) What you are saying is that stretching just makes the tube wall thinner, right? Thinner means that the OD is a smaller diameter, while the ID is a larger diameter...due to the material being stretched out? Link to comment Share on other sites More sharing options...
slflr Posted May 14, 2008 Share Posted May 14, 2008 Brownells just told me their fixture will not remove material from the barrel rib or the underlug. It looks like I'll need a lathe after all. Maybe one of those mini lathes from Harbor Freight? The material in the area of the rib and underlug can be removed with the judicious use of a file. Link to comment Share on other sites More sharing options...
Toolguy Posted May 14, 2008 Share Posted May 14, 2008 Brownells just told me their fixture will not remove material from the barrel rib or the underlug. It looks like I'll need a lathe after all. Maybe one of those mini lathes from Harbor Freight? A good file is a lot cheaper than a lathe. You can get the job done that way. Don't buy a Harbor Freight mini lathe. Those are junk. They will fight with you instead of help you. For a little more money you can get a mid size lathe from Grizzly. The smallest one I would get is the 10" by 22" model G0602 for $995.00. You would be much better equipped with the 12" x 36" gunsmith lathe, model G4003G at $2795.00. Whatever you buy, you will have to use it for a long time, so get the best possible - even if you have to stretch a little. The enjoyment or misery will last long after the purchase price. Link to comment Share on other sites More sharing options...
Toolguy Posted May 14, 2008 Share Posted May 14, 2008 When it is stretched, the cross section of the tube wall develops an hourglass shape, becoming smaller on the outside and larger on the inside. The "hourglass" description throws me off, as I think of an hourglass as caving inward too. (and, I was thinking of the tube as a whole...makes more sense just to think on one side of the tube...the wall) What you are saying is that stretching just makes the tube wall thinner, right? Thinner means that the OD is a smaller diameter, while the ID is a larger diameter...due to the material being stretched out? You are correct. Remember - we're only talking a thousandth or so. If the barrel is thin enough to stretch like that, I wouldn't want it on my gun. I would say the barrel in question should be replaced regardless of how the bulge got there. I think that is the real bottom line. Link to comment Share on other sites More sharing options...
Carmoney Posted May 14, 2008 Share Posted May 14, 2008 I guess I think the bottom line is if it shoots OK, leave it alone. 1" at 15 yards isn't a problem for the games people play with a 625. Link to comment Share on other sites More sharing options...
Toolguy Posted May 14, 2008 Share Posted May 14, 2008 I guess I think the bottom line is if it shoots OK, leave it alone. 1" at 15 yards isn't a problem for the games people play with a 625. Mike is right - it's just a matter of what standards one finds acceptable. Link to comment Share on other sites More sharing options...
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