hello, just signed up,like to say hi to everyone and thanks for any advice or education i may get,and if i can contribute in any way i will. pretty new to firearms,i have been shooting for years but i never really dissassembled or refinished any.i have lately gotten into stock refinishing. i am very religous about cleaning and storing all my firearms,and i have never had a problem...ever with any of them.they always fire and eject as exspected. i however have a vexing problem with a s/w 645 a friend gave it to me for a gift(birthday)last year,i really like the gun,i like how it fits my hand,i am somewhat accurate with it,and i love stainless handguns. it has actually has me into gunsmithing because of the problem it has. i can shoot a magazine through it one time,everything works flawlessly..then with no rhyme nor reason,it will out of the blue..fire multible rounds with a pulll of the trigger.not only do i find it disconcerting when it happens but i feel it is a dangerous condition.from what i understand it is firing out of battery?i tried rotating magazines,to no effect.i have dissassembled it down to every component and cleaned and lubed,and it stills does this.i studied the schematic for it and the only thing i can think of is possibly the sear is worn? am i missing something obvious,or should i just buy a new sear?can anyone help me with this..i will not shoot the firearm in this condition but i would like to fix it myself,as i have now had it apart so often i can assemble it with my eyes closed. no offence to gunsmiths but i would like to fix it myself,i replaced a few components(the levers or whatever you would call them)cant think of the names of the parts off the top of my head,but this is my first problem/project. i looked over the schematic and some of the levers/disconnect/pieces looked worn so i replaced them.i did not touch/change any springs though. i just cant understand why it would be as random as it is if it was a spring,i would think it would either work or not? i guess i could think the same about the sear. any help would be appreciated,and thanks in advance.