PUBLIC Forums => Public Forums => Technical Assistance => Topic started by: 2bnag on May 19, 2010, 06:13:21 PM
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Twice during the last two years I have picked up 9mm brass from our local range that has a very unusual mark from the firing pin. There is no dimple, just a "smearing" of the brass from the primer. Can anyone tell me what kind of weapon left this mark?
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Could be a S&W sigma series pistol. The primer has flowback into the apperture and then gets sheared as the cartridge case is ext/ejt.
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Looks a lot like the firing pin impression produced by an SWD Cobray M11-Nine.
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Kel-tecs sometimes have the flowback/shearing combo.
It's tough to see from the pictures. Are the breechface marks parallel? if so, that would rule out the M-11 which is concentric.
Better pictures, and a few more examples may help.
Chris
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I'm with Jeff . . . just had a Sigma CCs looked very similar to the one in the photos.
CMC
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It is not an SWD. I have a registered SWD 9mm and the dimple in the primer looks like most other fired rounds. Here is another view with two other fired 9mm from "normal" pistols.
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Could it be that this is caused by excessive pressure?
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I don't think it is excessive pressure as there are no other signs (like the primer "flattened"). Here is one more view again with two "normal" fired cases. In place ot the normal dimple, the primer actually has what looks like scraped brass. I cannot imagine how this round was fired.
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I've frequently seen Remington ammunition (UMC in particular) leave what I would call a "full aperture shear" where there is little or no actual firing pin dimple remaining but one giant aperture shear mark in its place. Seems to be ammo related because other ammo with the same guns don't seem to do this.
Gun type would have to be a droping barrel recoil so drag mark may be evident.
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Hi,
If there are "Firing pin drag marks" inside, this is a CBP type for sure.
I often seen this hapend, probabley whan the barrel movement is faster than the firing procedure.
I'll advice you to take a look at the French MAB. Also it is a CBP type, the barrel rotates 1/4 of a turn insted of moving up-and-down. That leeves strange markings.
Lior :-0
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With that new picture I agree it's not an SWD. The first picture had the appearance of a rectangular firing pin impression with circular firing pin aperture. Optical illusion I guess.
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I've seen this on the newer Sigmas after they changed the design to get away from the Glock patent infringement.
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I've probably worked a half dozen or so cases where I've seen this. A few were test fires. It seems to be some sort of gun/ammo combination that just doesn't work well together. I'll have 2 test fires with type A ammo look normal, and the other 2 with type B ammo have that flowback/shearing that doesn't appear to be a FPI at all.
The ones I've seen that look just like that have been plain ol' hemispherical firing pins and none have been the same make gun. So pick a gun, any gun, and it might be the winner.
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My Tanfoglio IPSC pistol in 9 mm Luger has a small diameter firing pin in a large firing pin hole. Even with the most moderate ammo (S&B) it shears the primer off in the firing pin hole.
Probably a light firing pin (minimum inertia) is adding to this.
From the shear marks it is obviously a locking system with a dropping barrel (Browning and similar)
I would not concider it typical for a specific firearms type but for a specific combination of tolerances.
Greetings
Axel
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"...There is no dimple, just a "smearing" of the brass from the primer. Can anyone tell me what kind of weapon left this mark...?"
:D I like "pick a gun...".... ^-^
"Smearing" isn't too unusual. It's just that there aren't that many manufacturers that have "straight/vertical" breechface marks. (So don't give up in the identification of this weapon!)
(If coarse "vertical" [and parallel] breechface marks is what I'm seeing...my initial "horseback opinion" was associated with a Ruger).
Is there any particular shape you can ascribe to the extractor mark?
A clear photo (or sketch) of the ejector mark can be very helpful—if not definitive.
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I've seen that happen on both some Sigmas and Kel-Tecs that have come through our office. One Kel-Tec comes to mind where the firing pin impression was totally covered by the shear.
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I agree with Jamie...very KelTec-ish
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Last month I had a Smith & Wesson SW9VE (newer style Sigma) that exhibited this type of FP aperture shear all around with only a very small bit of the FP impression still visible. This type of shearing was only displayed on my two Remington TF's... my Winchester TF's looked normal with only minimal shear right at the tip of the FP drag.
Not saying that another make/model firearm couldn't leave a similar mark though...
Z.
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Here are two examples of the same kind of thing:
The first is a pair of different .357 magnum ammunition fired in the same gun (Remington on the left) and the second is a pair of 10mm reloads also fired in the same pistol (primer type not known).
I've seen this "full aperture sheer" a number of times and while it's not always consistently reproducible, I have noticed it to be a lot more common with Remington ammunition and higher pressure ammunition.