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Thread: Question for those running LMT E-Carriers

  1. #1
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    Question for those running LMT E-Carriers

    For those who are running LMT E-Carriers with standard bolts, have you noticed excessively tight fit between the bolt and the carrier?

    I just received a new Enhanced carrier from LMT and found that the BCM bolt from my existing BCG was a very tight fit when I tried to swap it over. The BCM bolt has approximately 5k rounds on it. I tried a new PSA bolt and it seemed to fit better but was still a little tighter than with the PSA carrier. I plan on trying some other bolts that I have tonight but was curious whether others had experienced similar issues.

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    Are you saying that the body of the bolt is tight in the bore, or that the gas rings drag in the bore, or something else?

  3. #3
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    My newest gen E-carriers with BCM bolts' gas rings, I thought were a little tight, but still functioned fine. Assuming that is what you are referring to.
    Philippians 4:13

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    I apologize for not providing enough info. At first I thought it was the gas rings that were binding, so I removed them. It appears to be the body of the BCM bolt that is tight. With force, I was able to get the BCM bolt in but it definitely doesn't drop right in. I worked the bolt in and out of the carrier a little bit and it seemed to loosen up a little.

    I can't really tell if it's the bolt tail or another dimension of the bolt body that is interfering.
    Last edited by BC98; 03-23-16 at 22:00.

  5. #5
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    Yes, my bcm bolt was very tight, I called lmt and this is by design. The PD range staff didn't think it would function but it did

  6. #6
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    Are witness marks present from contacting components on the parts?
    There's a lot than can happen. Everything from dimensional interference to warped parts. Sometimes it's nothing, other times it is something else.
    There isn't a lot of information to go by, so about any additional input could help.

  7. #7
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    No witness marks that I could see. I tried 4 more bolts (2 Colt, another BCM, and a NiB from St. Croix Tactical) and all seated fully in the carrier with minimal force after I removed the gas rings. I tried measuring some of the diameters on the different bolts (bolt tail and various points on the body) but my calipers don't have the necessary precision to notice a difference in the dimensions.

    The suspect BCM bolt will seat all the way after some cycle of the PSA bolt through the carrier. I assembled the BCM bolt in the E-carrier and hand cycled it in my upper. There is definitely more resistance during cycling of the firearm with the tight BCM bolt than when the PSA one was installed. I THINK the resistance is coming when the bolt tail is starting to enter the channel it rides in during operation. There appeared to be enough clearance (~.003") for the main body of the bolt.

    BCM bolt installed until resistance is met:


    PSA bolt installed and fully seated for comparison:


    After going through all of the bolts I ended up installing the other BCM (one that fit) in the E-Carrier and will try running that for a while.

  8. #8
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    Quote Originally Posted by BC98 View Post
    No witness marks that I could see. I tried 4 more bolts (2 Colt, another BCM, and a NiB from St. Croix Tactical) and all seated fully in the carrier with minimal force after I removed the gas rings. I tried measuring some of the diameters on the different bolts (bolt tail and various points on the body) but my calipers don't have the necessary precision to notice a difference in the dimensions.

    The suspect BCM bolt will seat all the way after some cycle of the PSA bolt through the carrier. I assembled the BCM bolt in the E-carrier and hand cycled it in my upper. There is definitely more resistance during cycling of the firearm with the tight BCM bolt than when the PSA one was installed. I THINK the resistance is coming when the bolt tail is starting to enter the channel it rides in during operation. There appeared to be enough clearance (~.003") for the main body of the bolt.

    BCM bolt installed until resistance is met:


    PSA bolt installed and fully seated for comparison:


    After going through all of the bolts I ended up installing the other BCM (one that fit) in the E-Carrier and will try running that for a while.
    Is your extractor retaining pin perfectly centered?


    Sent from my iPad using Tapatalk

  9. #9
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    Quote Originally Posted by punkey71 View Post
    Is your extractor retaining pin perfectly centered?


    Sent from my iPad using Tapatalk
    It is.

  10. #10
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    Have you tried a bare LMT bolt?
    I obviously haven't tried out every bolt on the market, but there are reasons that I keep a stock of KAC, Colt, and LMT bolts with their accessorize. Until I find a reason not to do so, I'll keep a stock of them over the others on the market.
    Not saying that others are bad, but i'm not convinced enough to have the others readily available at hand.
    Again, not saying others are "bad", maybe I need more convincing?

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