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Thread: Looking for 1/7, 16 inch, chrome lined, mid length barrel

  1. #11
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    Re: headspace guages, and gunshow vendors

    Quote Originally Posted by C4IGrant View Post
    It isn't just my opinion. Any and everyone that has used their products has been overly happy.


    So you are using a go/no go gauge like this one: http://www.brownells.com/aspx/ns/sto...DSPACE%20GAUGE and the carrier is completely flush with the end of the upper receiver???

    Where your story becomes even more interesting is the comments about the vendors at the gun show not liking BCM. I am curious what kind of comments they made? Have they ever seen a BCM product (especially since NONE have been available for more than a year). So how could they have a negative opinion of a product they have never actually seen?


    C4
    Grant, the specific gauges involved are:

    Brownells P/N 184-000-036 (Clymer NO GO for 5.56) Dimension is etched on the side of the gauge, but I don't recall what it is. (I'm at the office)
    and
    Brownells P/N 319-223-467 (Forster NO GO for .223) for this gauge the dimension is 1.4666 in. as noted in the catalog web page.

    The bolt(s) were stripped, gauge inserted into chamber and the bolt(s) inserted and rotated by hand. Lots of slop on the bolt closed over the NO GO gauges. I don't own a field gauge.

    Vendors at gunshows tend to be similar to vendors at carnivals. You assume BS until data shows otherwise.

    As to BCM, yes I have contacted them by email prior to posting here. The upper is new and unfired (by me). I got a pretty quick reply requesting I send it back. I posted here in part to get some feedback on the reputation enjoyed (or not) by BCM in the community. They seem to have a pretty good one. I also am interested in who else to do business with if BCM can't (or won't) correct the issue in a timely fashion.

    I'm an "amatuer" gunsmith (mostly self taught) and full time engineer (education and vocation). I think I'm competent on the basic stuff. Measuring headspace is pretty basic.

    woofe

  2. #12
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    Quote Originally Posted by C4IGrant View Post
    Just for fun, I picked a BCM upper out of a pile and coupled it with an LMT BCG. I inserted my go/no go gauge and everything checked out.


    C4




    Yep, that is pretty definative.

    woofe

  3. #13
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    Re: NO GO gauge for 5.56/.223

    Grant:

    What is the dimension on the NO GO gauge you used to measure the headspace on the upper shown in your picture....... I ask this question due to the gauge you referred me to in the Brownells catalog.

    The Forster NO GO Gauge listed at Brownell's Website is 1.4666 in. As I say, I'm not at home to see the etching on either of my NO GO gauges.

    Am I to understand that BCM chambers their uppers that loose intentionally????

    woofe

  4. #14
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    Quote Originally Posted by woofe View Post
    As to BCM, yes I have contacted them by email prior to posting here. The upper is new and unfired (by me). I got a pretty quick reply requesting I send it back. I posted here in part to get some feedback on the reputation enjoyed (or not) by BCM in the community. They seem to have a pretty good one. I also am interested in who else to do business with if BCM can't (or won't) correct the issue in a timely fashion.
    Regardless of the actual issue, I'm confident BCM will take care of you and you'll have a fully operational upper in a timely manner. And when they do, you'll have the best value in uppers on the market. BCM quality is top-notch (even though it's possible you got a rare lemon, it happens to the best) and if I were ordering a new mid-length upper, I'd pick the BCM over the Sabre (close 2nd), and over the Denny's or CMMG upper anyday.
    --Josh H.
    Zombies seek out and eat brains. Don't worry; you'll be safe if they attack.

  5. #15
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    with the QC at BCM I find it hard to beleive they would let that happen,a finish blem maybe but never a problem like that.
    WHO ME ? ---- A government big enough to
    give you everything you want, is
    strong enough to take everything
    you have.
    -- Thomas Jefferson

  6. #16
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    Quote Originally Posted by woofe View Post
    Grant, the specific gauges involved are:

    Brownells P/N 184-000-036 (Clymer NO GO for 5.56) Dimension is etched on the side of the gauge, but I don't recall what it is. (I'm at the office)
    and
    Brownells P/N 319-223-467 (Forster NO GO for .223) for this gauge the dimension is 1.4666 in. as noted in the catalog web page.

    The bolt(s) were stripped, gauge inserted into chamber and the bolt(s) inserted and rotated by hand. Lots of slop on the bolt closed over the NO GO gauges. I don't own a field gauge.

    Vendors at gunshows tend to be similar to vendors at carnivals. You assume BS until data shows otherwise.

    As to BCM, yes I have contacted them by email prior to posting here. The upper is new and unfired (by me). I got a pretty quick reply requesting I send it back. I posted here in part to get some feedback on the reputation enjoyed (or not) by BCM in the community. They seem to have a pretty good one. I also am interested in who else to do business with if BCM can't (or won't) correct the issue in a timely fashion.

    I'm an "amatuer" gunsmith (mostly self taught) and full time engineer (education and vocation). I think I'm competent on the basic stuff. Measuring headspace is pretty basic.

    woofe

    I think I see where the issue is. First, go/no go gauges (field) are meant to be used with the BCG attached (as seen in my above). You look to make sure that a small portion of the bolt carrier is sticking out the back end of the receiver. A field gauge will generally measure around 1.4736.

    To measure head space, you will first need to remove the ejector. I see no mention of you doing this. Second, it appears that you have at least one gauge that is 1.4666. If a bolt does not lock up tight against this, it matters not as it is just one size in a range that is acceptable. For instance, John Noveske sent me his head space gauges for his barrels. There is an allowable RANGE between each barrel length. While I am not allowed to share his requirements, I can tell you that 16", chrome lined barrels have the WIDEST RANGE of them all. So just because the bolt is sloppy with one or two gauges, means absolutely nothing and to be perfectly honest, all of those bolts you tested would (most likely) work just fine with the BCM upper.

    You are trying to "fit" a bolt with only one or two size gauges and are wanting them to fit in a VERY NARROW range. In all honesty, you should have at least 10 gauges and run each bolt against each gauge.



    C4

  7. #17
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    Re: Headspace

    Grant:

    I appreciate the need to keep proprietary information just that.

    When I say I stripped the bolt, that includes the removal of both the ejector and extractor assemblies.

    As I implied, but did not directly say, I do not mount the bolt to the carrier. I insert the NO GO guage (1.4666 in.) and then insert the bolt and rotate by hand. In this case, the bolt easily rotates and you can "feel" some slop/play. I interpret this to imply I have about 0.002 or so additional clearance in the chamber with that bolt/gauge combination. I have used the above technique in place of having additional gauges to accurately tell me what clearances I actually have.

    You are absolutely correct, I need a range of gauges in 0.001 increments to do this with the most accuracy. But, up to this point I was not willing to expend the resources to acquire the gauges........ It seems clear that I need to get a third or even fourth guage to better bracket the boundaries of where I need to be worried.

    The gauge you referred me to measures 1.4736 in. The Forster field gauge measures 1.4696 in. The implications seems to be I need both so that I can bracket headspace ranges. I see the need to have a better understanding of what headspace is acceptable for various AR-15s. The range from the GO Gauge to the gauge you directed me to is 0.010 in., that is a lot. Upto this point I viewed the Field Gauge at 1.4696 in. as a drop dead brick wall. If not that, what is actually correct. And what is reasonable to expect of a new upper?

    Getting back to the immediate issue of my BCM upper, it appears that I may not have an issue after all (Ha Ha the sky is falling!). I plan to call BCM tomorrow when they have phone hours to try to get additional input.

    Any additional input you can make without violating you confidentiality agreement would be appreciated.

    woofe

  8. #18
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    Quote Originally Posted by woofe View Post
    Grant:

    I appreciate the need to keep proprietary information just that.

    When I say I stripped the bolt, that includes the removal of both the ejector and extractor assemblies.
    Roger.

    As I implied, but did not directly say, I do not mount the bolt to the carrier. I insert the NO GO guage (1.4666 in.) and then insert the bolt and rotate by hand. In this case, the bolt easily rotates and you can "feel" some slop/play. I interpret this to imply I have about 0.002 or so additional clearance in the chamber with that bolt/gauge combination. I have used the above technique in place of having additional gauges to accurately tell me what clearances I actually have.
    You are only supposed to use the bolt carrier on a "field" gauge. When "fitting" a bolt you do not put the bolt back into the carrier.

    If the bolt rotates on a 1.4666 gauge, that is fine and that bolt would be safe to use. While I would not classify that as a "fitted" bolt (as you need to feel some resistance when turning the bolt) is perfect for a combat weapon (which is what the BCM upper is).

    If you want a "fitted bolt", you would go up a couple sizes in gauges (in the allowed range) till you found a bolt that did not spin easily.

    You are absolutely correct, I need a range of gauges in 0.001 increments to do this with the most accuracy. But, up to this point I was not willing to expend the resources to acquire the gauges........ It seems clear that I need to get a third or even fourth guage to better bracket the boundaries of where I need to be worried.
    You ONLY need a full set of gauges IF you are trying to "fit" a bolt. I would deem this as not necessary on a chrome lined, combat gun.

    As a general rule, the manufacturer would set the standards for the allowable range (not the consumer). You can of course make up your own standard if you like.

    The gauge you referred me to measures 1.4736 in. The Forster field gauge measures 1.4696 in. The implications seems to be I need both so that I can bracket headspace ranges. I see the need to have a better understanding of what headspace is acceptable for various AR-15s. The range from the GO Gauge to the gauge you directed me to is 0.010 in., that is a lot. Upto this point I viewed the Field Gauge at 1.4696 in. as a drop dead brick wall. If not that, what is actually correct. And what is reasonable to expect of a new upper?
    To be perfectly honest, all you need on a chrome lined, combat AR is a "field" gauge. Fitting a bolt on a chromed lined AR is really a waste of time and not something I would get wrapped around the axle about.

    Getting back to the immediate issue of my BCM upper, it appears that I may not have an issue after all (Ha Ha the sky is falling!). I plan to call BCM tomorrow when they have phone hours to try to get additional input.

    Any additional input you can make without violating you confidentiality agreement would be appreciated.

    woofe

    I would suggest sending the upper back to BCM as I am sure Paul would like to take a look at it. That way everyone can be sure that everything is ok.



    C4

  9. #19
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    Re: Headspace on my BCM upper

    Grant

    An Update:

    I stopped by a buddy's place and he had a Forster Field Gauge at 1.4696 in. This gauge will not allow the selected bolt to even start to close. First I used my hand technique as described above. Then I put the stripped bolt into a carrier and again it would not close. Looked like your picture

    I think this is a good thing

    woofe

  10. #20
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    Re: more headspace

    This has been a learning experience...........

    More data. A cop buddy stopped by late last night. We pulled down his Colt LE carbine (sorry it was late I don't remember the model). Without going into gross details, it headspaced very similarly to the BCM upper. Pulled an SP1 (holding it for an other buddy) out of the back of the vault and checked it. Results were similar to the Colt LE carbine.

    Hmmmmmmm..........the differences between weapons intended for sport and and those intended for combat.

    The engineer part of me is having a whale of a good time, but it looks like I stirred up a bunch of "stuff" that didn't need to be.

    Had more email contact with BCM. I will be sending it back for them to check out.

    They are ready, willing, able, and eager to stand by their product.

    Thanx to all.

    woofe

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