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Underwood 10mm Ammo - extractor marks on rim??

Discussion in 'The 10 Ring' started by copo9560, Jun 27, 2012.

  1. copo9560


    Feb 21, 2012
    Last night at the range, firing G20SF (all stock including spring), the brass I was collecting all had marks on the rim - looks like coming from the extractor. I can't seem to get a good picture to post but it looks like a small gouge in the case rim - on all of the cases. Ammo was Underwood 165 Grain flat nose ammo, listed at 1400 fps on the box.

    Ammo shot great but I have not seen this mark on other cases. I have shot local made ammo, Double Tap and Winchester Silvertips with no issues.

    Curious what would be causing this. The marks look like they can be dressed with a small file for reloading. Any suggestions or ideas?
  2. To copo9560. I think you are right, that you are looking at extractor marks. I shoot Underwood ammo and I get this on my cases. I don't worry about them as I do not reload. My Underwood ammo functions flawlessly in my G20SF. That is my main concern. I give all my empty cases to a friend who reloads and he has never complained to me that this mark has negatively effected his reloads. My suggestion is to keep shooting and have fun.

  3. _The_Shadow

    _The_Shadow Ret. Fireman

    Jul 23, 2007
    Southeast, LoUiSiAna
    You could try a different recoil spring with a little extra wt. to see if the dwell time holds the slide battery in lockup just a litte longer and possibly eliminate the extractor scar.

    What maybe happening is the unlock is starting and the extractor is dragging the casing back before the pressure has dropped enough to release the case from the chamber wall. If the impulse was more you might see bulged or smiled casing or worst a "case blowout"! The recoil spring change out is fairly cheap considering other issues.
  4. dm1906

    dm1906 Retired SO

    Sep 7, 2010
    PRK (Kalifornia)
    It could also be the ejector. If it's misaligned, it will gouge the case head, and usually also a little of the case wall. Use a Sharpie marker and mark the case head, from the center of the primer to the edge of the rim. Load the round with the mark at 12 o'clock, fire it, and see where the mark is in relation to the extractor and ejector. The ejector sticks up and can get dinged or snagged when the pistol is disassembled. Also, measure the case head diameter before and after firing. If the rounds are overpressure, they can expand the case head to the point the extractor and/or ejector doesn't engage correctly. As a last possibility, the rounds may be so overpressure they are resisting initial extraction (case wall traction) during an early unlock from battery, and/or resisting the little slide down during battery unlock. I've seen this happen (personally), and the extractor can rip a chunk out of the rim. I posted a pic of the cases in another thread some time back. I'll see if I can find it.....
  5. cowboy1964


    Sep 4, 2009
    Curious why an ejector mark would be limited to one specific brand of ammo. Is there something weird about Underwood's cases?
  6. copo9560


    Feb 21, 2012

    I believe they are Starline brass. Difference between Underwood and others is pressure - they are far hotter than the DT and Silvertip ammo I also have used.
  7. Bro KV

    Bro KV

    May 9, 2012
    I am using UA 155gr ammo through my 20SF and am also getting gouged casings. Should I change my recoil spring?
  8. WeeWilly


    Nov 12, 2011
    I get some extractor rash on my Starline cases when I am running my hotter loads. This is both with my G20SF and G29SF. On my G20SF I have run a 22lb captive ISMI RSA and also a 24lb of the same thing. Never run the stock spring anymore.

    The ironic thing is I haven't gotten any on the Underwood I have shot.

    In any case, the gouges I get are not very deep, I can still slide the cases into my Dillon shellplate when I go to reload and they feed fine in subsequent loadings, always lighter loads though. I only use new brass for my twilight zone loads.