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Greetings! I need a little help and/or info please. I recently got lucky and acquired a Model 15-3 4" blue that is one of those guns that appears to have been carried some, but never or seldom fired. The problem I have is with the mainspring strain screw. The one on this gun does not screw into the front strap far enough to seat flush. When screwed in as far as it will go, the head of the screw sticks out almost 1/4". This is even though(as with lots of older guns) some previous owner has filed the screw down to cause a light trigger pull. I took a chance and bought a factory new screw, to solve the shortened screw problem at least, and this new screw only goes into the grip frame to the same exact depth as the original.

I have never encountered this problem before, and am stumped. Has anyone else ever had the same problem and if so, what did you do about it?

Thanks in advance for your help!

:bluelogo:
 

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You might take the screw to Ace Hardware and find a similar screw that is shorter and with a smaller (thinner) head.
 

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welcome01 to the forums from the Wiregrass! It sounds like the threads in the grip frame are galled. Possibly by someone using a non-S&W screw. DON'T try to fit a screw from a hardware store. The threads on S&W handguns are different than standard threads...48 tpi, IIRC. Find an old gunsmith that has the taps to chase those threads. It may be that he will have to retap it to a different thread. But, that should be your last resort.
 

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Where are you located? I have the taps to dress the threads. Don't use hardware screws - like Guy said that's likely the origin of the problem. Hardwares don't have the taps available, they must be ordered from Brownells or Midway, etc.
 

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Not exactly on topic, but a tip I thought I'd pass along from an old timer gun guy I used to work with; if you ever come across an old junk sewing machine, remove and save all the screws that you can, of all sizes. They often have the same threads that are found on guns. I've found a couple of tossed machines over the years set out for large trash collection and have about half a pill bottle full of various sized fine-threaded screws. I have only used one and it wasn't for a real gun, but a BB gun and it worked perfect!
 

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Take off the stocks and check to see if the the mainspring has been shimmed where the strain screw butts up against it. I have heard of some doing this in an attempt to change the trigger pull. That could keep the screw from tightening flush.
John
 

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6-48 is the most common gun screw, this translates into #6 diameter & 48 threads per inch.
 

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Make a list of things that you need at the same time, Brownell's sells screws.......and anything else for guns, because the shipping for one screw is KILLER!!!!! Might as well ship sweveral items for the about the same price. I once bought 2 springs for $1 each......the shipping was $6!!!! :eek: Bob
 

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You don't need to be buying any screws. You already have a strain screw that unless the threads are messed up should work fine. What is needed is the tapped hole in the frame needs to be chased and the threads cleaned up. It would be best to have a gunsmith do that so that the proper tap is used.
 

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You don't need to be buying any screws. You already have a strain screw that unless the threads are messed up should work fine. What is needed is the tapped hole in the frame needs to be chased and the threads cleaned up. It would be best to have a gunsmith do that so that the proper tap is used.
Yup, plus inspect for Timetripper's thought about a shim or bushing on the spring. You've gone through 2 screws, that's likely not the source of the problem.
 

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Discussion Starter #13
Located in NE Oklahoma. Thanks for the advice:) Thanks all of you. My quick fix has been to reduce the head of the screw and re-crown it so that it goes in far enogh plus now fits flush with the grip frame. Thank God for Dremel tools:) Will try the thread doctoring next.
 
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