This topic contains 2 replies, has 2 voices, and was last updated by  Goodsteel 1 year, 7 months ago.

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  • #48115
     JRR 
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    I have a CZ 75B SA.  40 S&W.

    Installed a new minimum tolerance bushing in slide.  Muzzle O.D. .550 and bushing I.D. .550″.  Tight, solid lockup.

    Tested several loads with cast RCBS 180gr bullet.  Full magazines functioned ok except last round would jam up and mangle.  Tried several mags, with same result.

     

  • #48116
     JRR 
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    Barrel is difficult and tight to install and requires much wiggling to get it to fit into slide.

    I tried all kinds of things to get it to not mangle last round in chamber.

    Finally removed the extractor and spring.  Didn’t see anything wrong.  Decided to order a new extractor and spring.  When comparing new to old, it appeared the old had eroded slightly and the old spring was half the length of the new.  Installed new parts.  Most of crunching was gone, but not all.

    Took out barrel, taped up the first 5/8″ at muzzle, chucked it in the drill press.  Sanded the barrel O.D. between the tape and lugs to remove .oo2″.  My theory was the barrel was dragging and slowing down the slide velocity.

    Bingo!  Perfect function and greater accuracy due to tighter lock up.

     

  • #48120
     Goodsteel 
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    You did exactly the right thing. This happens with 1911’s that have too tight of a bushing as well which will cause the lugs to drag the slide, and basically muck up the works by not letting the barrel run through it’s motions effortlessly. I’ve built and customized pistols for precision shooting and it’s vitally important not to take precision too far. There’s a balance that must be struck and “the whole is greater than the sum of its parts” is the way you get the best out of a SA firearm. Line to line fit is rarely a good thing.

    Glad you got it running correctly!

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