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Just an observation and curiosity. Hopefully Maverick will forgive me for snagging this photo from another thread.

I'm checking out a .357 SIG Compact, and on the underside of the slide, there's a very small ledge. Not the part of the slide that contacts the front edge of the locking block when it's fully into battery, but when it unlocks, it's the initial underside part of the slide that rides along the top of the locking block.

It can be seen pretty well in this photo. The circled part - you can readily see the bump/ledge on the underside.

None of the 9, 40 or 45 Compacts have this, and are perfectly flat, but this particular .357 I'm looking at does. Any clue why? Or anyone else here that has it on their slide?

Thank you kindly.

 

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357sig is essentially a necked-down 10mm case...this is probably a result of engineering to get the odd cartridge to cycle properly...the USPf never got chambered in 357sig because of cycling issues...the locking block design on the USPf is different which leads me to believe that you have found the magic change that made the USPc awesome in the caliber....
 

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357sig is essentially a necked-down 10mm case...this is probably a result of engineering to get the odd cartridge to cycle properly...the USPf never got chambered in 357sig because of cycling issues...the locking block design on the USPf is different which leads me to believe that you have found the magic change that made the USPc awesome in the caliber....
It's a necked down 40 to .355 (9mm), the 10 is a mite longer.
 

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i calipered an empty 357sig case and a 40 case after i posted it...good catch :)
It's all good, and I can see how that could be thought because the 10mm Auto is the parent of the 40 S&W, and the 40 S&W the parent of the 357 SIG. Just a point of clarification for the reference of this thread.
 

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Now to get real knit-picky. The .40 is not the parent of the .357 SIG either. If you size a .40 case down to .357 SIG it will not work. It will be too short and since the .357 SIG headspaces on the mouth instead of the shoulder like it should have, the headspace will be wrong if you just run a .40 case through the .357 resize die. Parent case, closer to a trimmed 10mm or a .40 unformed case that has not been trimmed to length yet, but neither the 10mm nor the .40 S&W are really parent cases. You could use the 10mm if you trim and neck ream if needed, but you cannot use the .40 S&W case at all.
 

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Now to get real knit-picky. The .40 is not the parent of the .357 SIG either. If you size a .40 case down to .357 SIG it will not work. It will be too short and since the .357 SIG headspaces on the mouth instead of the shoulder like it should have, the headspace will be wrong if you just run a .40 case through the .357 resize die. Parent case, closer to a trimmed 10mm or a .40 unformed case that has not been trimmed to length yet, but neither the 10mm nor the .40 S&W are really parent cases. You could use the 10mm if you trim and neck ream if needed, but you cannot use the .40 S&W case at all.
thats a valid point also...darn bastardized rounds...lol...if the 357sig rounds werent so expensive I would have kept my barrel for my uspc--fun round for range duty

thanks for the info--OP sorry for hijacking the thread a bit but some good info
 

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Now to get real knit-picky. The .40 is not the parent of the .357 SIG either. If you size a .40 case down to .357 SIG it will not work. It will be too short and since the .357 SIG headspaces on the mouth instead of the shoulder like it should have, the headspace will be wrong if you just run a .40 case through the .357 resize die. Parent case, closer to a trimmed 10mm or a .40 unformed case that has not been trimmed to length yet, but neither the 10mm nor the .40 S&W are really parent cases. You could use the 10mm if you trim and neck ream if needed, but you cannot use the .40 S&W case at all.
Interesting Big Bore, thanks. I always thought the SIG head spaced on the shoulder, but I have never reloaded that particular caliber. Good info, I stand corrected.
 
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