[oldgranpa]

\"Sliding chamber marks\"

Have any of you seen this with spent cartridge cases from your pistols........

From my 32NAA Guardian I am seeing what is known as "sliding chamber marks" on the spent cases. This is a burnished area on the front half of the case and 8x magnification shows tiny linear striations that confirm it is during extraction. An unfired chambered round does not show any such rub marks. This seems to say to me the Guardian chamber is slightly tapered toward the shoulder to achieve a tight seal during firing. I've had no problems at all in spite of this. I've even seen it on some .357Sig spent cases at the range. As if a bottleneck chamber has to be made this way to get correct headspace.

.....have you seen any such rub marks on spent cases?

Attached picture of holsters shows two spent cases that you can see the burnished area on the top half.

og

 

[flyandscuba]

og,

I may be wrong (and I'm sure I'll be corrected if I am)...but, I think that bottlenecked cartridges headspace at the shoulder of the cartridge rather than the case mouth.

I've seen the same markings on the brass out of my two pistols chambered in .357 Sig -- more noticable in the Steyr's spent brass than the KT.

 

[Flyer]

I may be wrong (and I'm sure I'll be corrected if I am)

Don't worry, F&S! You don't have to worry about being corrected!
Cause you're RIGHT!
oldgranpa,
Yep, I see that in tons of my guns... it's perfectly normal.
Also, remember that the Guardian is a blow-back pistol... which means the case starts backward as soon as the bullet starts forward, under full pressure! Marks like this are almost inevitable in these instances.
Flyer

 

[oldgranpa]

makes sense!!

Aha! By jove! that makes sense!! Blowback under high pressure!

Scub..are your .357Sig pistols blowback?

And I agree, headspace has to be at the shoulder so that kinda eliminates my theory about a tapered chamber.

Always great to compare notes with folks here at KTR.

og

 

[flyandscuba]

Nope, both .357 Sigs (KT P-357 and Steyr M-357) are locked breech pistols.