hovbuild Posted November 11, 2012 Share Posted November 11, 2012 I have my 625 with a 6.25 lb pull that has been very reliable for the last 10,000 rounds. It has a reduced main spring and is smooth as glass. It just started missing two out of fifty. Strain screw is tight, no binding, single action will fire the misses in double. Only thing I can figure is that I have been a bit lazy and the last 10 or so times the brass has been reloaded I have not cleaned the primer pockets. I also use just the same brass for the 625. I hand seat fed 150's, the firing pin was an extended one and I cleaned the area were the hammer contacts the frame. I did the trigger job myself about two years ago, maybe it's time to have Mike work on it. I will do another fifty and clean the primer pockets to see if it will help. Link to comment Share on other sites More sharing options...
okshootist Posted November 11, 2012 Share Posted November 11, 2012 Check for endshake. If you cut the end of the strain screw square, check to see if the edges have rounded. If you use loctite on the strain screw, look for buildup under the screw head. Check the rounds that do not fire to make certain the firing pin strikes are centered. Link to comment Share on other sites More sharing options...
Round_Gun_Shooter Posted November 11, 2012 Share Posted November 11, 2012 Put a spent primer between strain screw and main spring and see if it makes a difference. Springs can wear after a while Link to comment Share on other sites More sharing options...
Waltermitty Posted November 11, 2012 Share Posted November 11, 2012 Those are all good. Check the sides of the hammer for signs for dragging. If it is dragging it will have to be shimmed. As a footnote, I have never cleaned a primer pocket and I am well below your trigger pull. Link to comment Share on other sites More sharing options...
toothguy Posted November 11, 2012 Share Posted November 11, 2012 Check the firing pin spring. It can break and bind but still appear to give some push back on the firing pin. Link to comment Share on other sites More sharing options...
hovbuild Posted November 12, 2012 Author Share Posted November 12, 2012 (edited) Thanks for the help. There is no end shake that I can tell. Strain screw is square and clean. I will check the firing pin spring later though. As far as the hammer dragging it was shimmed and seems like it is the same as when I did the work on it.. I'll order a new spring and a firing pin. Good to have spares anyway. BTW I hate cleaning the pockets anyway, thanks for that. Again thanks, Bill Edited November 12, 2012 by hovbuild Link to comment Share on other sites More sharing options...
toothguy Posted November 12, 2012 Share Posted November 12, 2012 Thanks for the help. There is no end shake that I can tell. Strain screw is square and clean. I will check the firing pin spring later though. As far as the hammer dragging it was shimmed and seems like it is the same as when I did the work on it.. I'll order a new spring and a firing pin. Good to have spares anyway. BTW I hate cleaning the pockets anyway, thanks for that. Again thanks, Bill Apex tactical has a good one and they give you the spring as well I think is around $15. Link to comment Share on other sites More sharing options...
hovbuild Posted November 12, 2012 Author Share Posted November 12, 2012 Well I checked the end shake measurements and this just might be the problem. Pushed foward .001pushed back .0075. Also the barrel and cylinder have a 1/2 .001 differance left and right. I orders some shims... Bill Link to comment Share on other sites More sharing options...
Waltermitty Posted November 12, 2012 Share Posted November 12, 2012 Well I checked the end shake measurements and this just might be the problem. Pushed foward .001pushed back .0075. Also the barrel and cylinder have a 1/2 .001 differance left and right. I orders some shims... Bill That would do it. I order the thin shims and stack up what I need. Link to comment Share on other sites More sharing options...
hovbuild Posted November 12, 2012 Author Share Posted November 12, 2012 Walter do you know what spec is? I ordered 2 .002 and 2 .003 shims. Link to comment Share on other sites More sharing options...
Toolguy Posted November 12, 2012 Share Posted November 12, 2012 (edited) You want it fitted as closely as possible and still turn freely. Check it again after 1 or 2 hundred rounds, it may need another shim or a .002 traded for a .003. They tend to seat in at first, then stay the same for a while. Endshake will definitely cause misfires. Edited November 12, 2012 by Toolguy Link to comment Share on other sites More sharing options...
Patrick1981 Posted November 12, 2012 Share Posted November 12, 2012 I think with a reduced firing pin spring and one piece 0,002" endshake shim you are OK Anyway check the strainscrew.. a few blue loctite or a drop of nail paint to stop it. Link to comment Share on other sites More sharing options...
Waltermitty Posted November 12, 2012 Share Posted November 12, 2012 Walter do you know what spec is? I ordered 2 .002 and 2 .003 shims. I'll dig out my Kuhnhausen book this evening to confirm. About .006" barrel gap would be ideal, but to some degree you've got to take what you can get. The barrel gap dimension includes all of the tolerance stacking from the barrel fitting through the cylinder and star machining to the frame machining. Assuming your endshake measurement is spot on, I would start with .006" of shims and see how it all comes together. On a fresh endshake fitting on my guns I like to have just enough endshake to feel, but not necessarily enough to measure. If there is zero endshake or the cylinder is tight in the frame, try to go down .001" and assemble again. I give priority emphasis to the endshake dimension and let the barrel gap fall where it may. Over time the shims will wear so being a little close to start works best for me. Write down how many shims you use since this is where most of the wear will occur. Some of us think an endshake fitting is only proper when it includes one or more shims. I will face the crane to make sure. That way, after many thousands of rounds through the gun, you can just replace the correct number of shims and be back at that "just fit" performance. Link to comment Share on other sites More sharing options...
hovbuild Posted November 12, 2012 Author Share Posted November 12, 2012 (edited) Great help thanks. I have run real heavy loads ( 225 pf) for pin shoots. I think it put a little ware on my buddy. The firing pin was .003 + shorter than the new spare I have..They were the same when I installed the first one with a reduced spring they were factory replacements for the newer 625. They are .493 and .496... I have a real long pin in the draw .506 but I think these are the ones you can't dry fire, I think..Getting old and trying to remember were stuff is and what is is for can be a challenge ..LOL Also the strain screw shows a little wear so I will change that out when I get one. I also got a new reduced power main spring but I was under the impression that all leaf type springs don't lose power but I could be wrong. When I get the new one I will try a the old screw to see if there is a difference between old and new. Tough finding all these parts in one place for sure. Most on Midway, some cylinder and slide and then the shims from KLN shims. Edited November 12, 2012 by hovbuild Link to comment Share on other sites More sharing options...
Waltermitty Posted November 12, 2012 Share Posted November 12, 2012 Great help thanks. I have run real heavy loads ( 225 pf) for pin shoots. I think it put a little ware on my buddy. The firing pin was .003 + shorter than the new spare I have..They were the same when I installed the first one with a reduced spring they were factory replacements for the newer 625. They are .493 and .496... I have a real long pin in the draw .506 but I think these are the ones you can't dry fire, I think..Getting old and trying to remember were stuff is and what is is for can be a challenge ..LOL Also the strain screw shows a little wear so I will change that out when I get one. I also got a new reduced power main spring but I was under the impression that all leaf type springs don't lose power but I could be wrong. When I get the new one I will try a the old screw to see if there is a difference between old and new. Tough finding all these parts in one place for sure. Most on Midway, some cylinder and slide and then the shims from KLN shims. Page 27 of the Kuhnhausen book says .004" to .006" barrel gap is usual, with an enlargement with use. I've been happy on a high mileage gun with a gap crowding .008". I purchased two 625-8's about three years apart and they had two different length firing pins. Find a replacement pin you like and stick with it; you never can tell what you'll get from S&W. You can also get the shims at Brownells although their search engine is lame. Here's the link: http://www.brownells...s-prod9858.aspx Kuhnhausen also suggests you lengthen the yoke if you need more than .006" in shims, although that will take a step up in difficulty. Let us know how it all comes out! Link to comment Share on other sites More sharing options...
hovbuild Posted November 23, 2012 Author Share Posted November 23, 2012 Good morning, I thought I'd give you an update. I shimmed the cylinder .003 ( as much as I can go without affecting trigger pull) and it still missed one out of fifty. I had the longer factory firing pin in the gun for about a year (.494) and never had a problem. I had a clyinder and slide .504 pin in the drawer so I installed this and went through the inners making sure there was no binding. The other day a ran 15 clips through it and it was fine. I also noticed that the pull weight was at just under 6#. Thanks agian for all your help . Bill Link to comment Share on other sites More sharing options...
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