Cracked Op Rod
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Thread: Cracked Op Rod

  1. #1
    Newbie stiglitz-15's Avatar
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    Cracked Op Rod

    Hi Everyone, this is my first post and have been a member on here for awhile for info/resources regarding my xcr-l. I discovered this failure when I was going to clean the rifle, Approximately has 2000 rounds combined (5.56 & 7.62x39), it is a newer type 1(serial number in the mid 9000's). gun has been cleaned regular and inspected after each firing.

    There is a crack almost around the entire circumference of the op rod(I could break it by bending if I tried, it is that weak), beginning at the tang that rides in the bolt assembly. Cracked Op Rod-dsc_1180.jpgCracked Op Rod-dsc_1181.jpgCracked Op Rod-dsc_1182.jpg

    sorry, the crack is hard to see but it is there.

    My question is, is this a manufacturing defect? or related somehow to quality of parts? because 2000 rounds seems very low for such a major part to fail, I have read about other op-rod failures(At different points and round counts) But I do find this concerning, and thought I would bring awareness to the situation. Let me know what you guys think

    Thanks
    Last edited by stiglitz-15; 06-20-2015 at 03:57 PM.

  2. #2
    Marksman Benjamin Kurata's Avatar
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    Contact Robinson Arms ASAP. They should be able to replace this with no issues. As an aside, I have serial number 3XX and have the old, original op rod with the welded on lugs. I have over 10,000 rounds through my rifle with no issues -
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  3. #3
    XCR Guru Sean K.'s Avatar
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    Quote Originally Posted by Benjamin Kurata View Post
    Contact Robinson Arms ASAP. They should be able to replace this with no issues. As an aside, I have serial number 3XX and have the old, original op rod with the welded on lugs. I have over 10,000 rounds through my rifle with no issues -
    Agreed. Very uncommon....that said, I have a spare one piece op rod for that reason...it can happen. Doesn't mean it will or it's likely or common. If I were you...I'd contact RA, and get 2 coming your way.
    Merlin likes this.
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

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  5. #4
    Expert SLCXCR's Avatar
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    The wear on the front lug is unusual as well. It would be interesting to learn if that's an after effect of the crack or vice versa.

    Paul
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  6. #5
    XCR Guru Sean K.'s Avatar
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    The part that concerns me is that the one piece op rod was supposed to cure this problem....or so I thought. Obviously, either metallurgy needs adjustment or thicker material needs to be used. Though...this may be part of the reason for the new bcg design in addition to slam fires.
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

  7. #6
    Expert Mechanic's Avatar
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    Agreed. A stress fracture of that magnitude after only a couple thousand rounds screams steel quality issues. The damage on the front lug doesn't look like wear, it looks like impact the way the metal has squeezed over the edge. There should be only low forces on that side of the lug, so I find that interesting.
    "Don't Tread On Me!"
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  8. #7
    Newbie stiglitz-15's Avatar
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    Edit: Also as I forgot to add, around 500 rounds in the gun double fired(Second one slightly out of battery) and severely damaged the bolt cam, and bolt carrier jamming the rifle, those parts were replaced as result. I am now beginning to wonder if damage to the op-rod also occurred at this point in a microscopic way. Sorry for not mentioning this earlier.

    Yes, the wear is unusual. on the front lug(on oprod) its worn grooves on the bottom side edges(seems to have worn on 2 small edges from front of bolt carrier), as well as the bottom rear edge(Seems that the bolt cam is impacting or wearing the oprod) Also if you look on picture 2, on the side of the rear lug it is also beginning to groove on both sides where it rests in carrier. top of oprod has no finish left at very rear and in the top middle of oprod. Not sure if these are normal wear points, but seems concerning. Also to note, there is no grooving or significant wear on bolt cam or carrier (only finishing wear), the bolt lugs seem to have some minor peening/wear on the front and rear of lugs, seems to have developed from when the bolt locks in action but nothing directly related to oprod. So the oprod seems to be a softer material. Feel free to ask questions, as I am eager to learn more about the system and hopefully find the cause of this issue.
    Last edited by stiglitz-15; 06-20-2015 at 10:21 PM.

  9. #8
    Expert Mechanic's Avatar
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    Did RA replace the BCG? Certainly sounds related to the incident. I would think RA would be very interested in seeing it and knowing as much about the incident as possible. With a fracture like that, I don't believe any conclusions can be achieved as far as the additional lug wear.
    SLCXCR likes this.
    "Don't Tread On Me!"
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  10. #9
    Expert cjt50's Avatar
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    Not a common problem and the new 1 piece version is supposed to be "better"

    Actually I have cracked 2 of the older 2 piece version, same place as yours. There an old thread that I started awhile ago bout it. Haven't had an issue yet with the new 1 piece op-rod. When I contacted RA bout it, the answer I got was you are using too high of a gas setting. The golden silence I got on the other end of the phone when I told'em it was flinging brass 20 feet on the "S" setting was priceless.

    My issue turned out to be severe gas port erosion that was over gassing the rifle. Barrel had 20k rounds thru it when I finally scraped it.

    However that's the 1st newer 1 piece version I seen reported here. (oh gzzzzzz)
    "Tis better to be silent and be thought a fool, than to speak and remove all doubt." - Pres. A. Lincoln

  11. #10
    Newbie stiglitz-15's Avatar
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    Quote Originally Posted by cjt50 View Post
    Not a common problem and the new 1 piece version is supposed to be "better"

    Actually I have cracked 2 of the older 2 piece version, same place as yours. There an old thread that I started awhile ago bout it. Haven't had an issue yet with the new 1 piece op-rod. When I contacted RA bout it, the answer I got was you are using too high of a gas setting. The golden silence I got on the other end of the phone when I told'em it was flinging brass 20 feet on the "S" setting was priceless.

    My issue turned out to be severe gas port erosion that was over gassing the rifle. Barrel had 20k rounds thru it when I finally scraped it.

    However that's the 1st newer 1 piece version I seen reported here. (oh gzzzzzz)
    Yeah, I've been running about 10-15ft on setting 1, rubber buffer has also been in perfect shape since I bought it.

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