What kind of scarring? Are the lines longways on the case, if so they are caused by the two parallel rails on the bottom of the slide. You can lightly, very lightly polish the edges with some 400-600 grit paper and they should decrease significantly. Those rails guide the sear as it rides up onto the post during reset, so they are critical to the operation of the weapon.
Scarring similar to the notorious Glock "smiles"? I noticed the same thing, brand new M40A1, now 200 rounds through it. Looked to be a small dent transversely on the case about a quarter inch up from the rim. Checked maybe 15 fired cases after i noticed it on one and every one had the impression. I dont reload so i'm not all that concerned, but if its abnormal behaviour, maybe i should be.
on bottom of the slide the middle would be solid but it would interfere with the sear so to accomidate the sear they milled the middle sadly it has sharp ridges on both sides. its price payed for lowest bore axis.
little extremely light sanding and lots of polishing will take care of it.
yeah its similar to that, but not exactly the same - instead of an arced "smile" its a straight line impression across the case at about the same place pictured in the link i posted. no ballooning towards the base of the case either, its more of a dent.
planning on running another 1-200 rounds through the gun this weekend, i'll photograph some samples at the beginning and end of the session. Maybe just something to do with break-in. Might be the extractor spring just needs some loosening up.
what I have encountered is bottom 2mm of the case doesnt expand when fired which will create what looks like a ring around the case smaller than the brass above it but when sized for reloading will not size down. I have reloading casings like that a ton to no ill effect.
Those marks on the brass look deep and I'd wonder about how safe they would be to reload with. I never have seen anything remotely like that from any of the Steyr pistols I've had, but I would +1 on MrAp*'s "lack of chamber support" theory. <shrug>
And, I'd be very interested in what Jeff at SAI has ta say about it.
I did find a rather curious situation in a 6MM/22-250 Ackley Improved fireforming article leading to brass seperation that kinda resembled the Glockinbrassin' pics:
Though I really can't see how the 2 brass damage phenomena could share commonality, check the primers when you set up for your photo-shoot. If they show any signs of flattening, that would be of interest, as well. <shrug>
Finally got to the range yesterday, I collected 15 samples of spent brass from rounds 1-50 (PMC) and 15 samples from rounds 100-150 (Federal HST). The dents are much higher up on the case than i remembered, I'll get some pictures this evening.
Images as requested - the gun has a total of around 500 rounds through it now with zero feeding or extraction issues. The only hiccup i've had is a single misfire which i believe to be ammo related, the primer strike looked good. At times i do have a spent case bounce off the top of my head, but the gun cycles so well I'm hesitant to change anything. I have noticed a small dent in nearly all of the spent brass though.
Samples collected between rounds 1-50 of the day, PMC brand ammo:
Samples collected between rounds 100-150 of the day, Federal HST ammo:
Is this anything to be concerned about, or is it pretty much normal? Never noticed anything similar on the 9mm or .45 cases from any of my guns.