On the right side of the gun, above the trigger is a button, push that in and swing the slide release on the left side. Remove the button and spring, then pull out the slide release. To remove the barrel assembly simply push forward and pull off.
Reverse steps to replace it.
Dont try taking apart the grip. Those plates hold the mag release, safety, and trigger action in place. You run a big risk of losing the mag release spring if you take this section apart.
you pull back the slide and yank up the slide and viola its dissasembled
Recommend you find a good gunsmith.
You can get manuals at the Smith and Wesson website.
Ask a gunsmith for help
check out this video: In general, Sigma pistols disassemble like a Glock. http://www.youtube.com/watch?v=O7ws0gAQlpY
With no other information supplied, 100-500.
Best left to a trained gunsmith. For normal cleaning, no disassembly is needed.
Go to S&W's web site and request a owner's manual. They will send it to you for free.
About $400.
Smith&Wesson model 14
You can request or download a manual from the S&W website. If that doesn't work for you, find a good gunsmith.
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Smith and Wesson Chief's Special Model CS45