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Thread: Status of NEW Comparison Chart of Commercial M4-pattern carbines

  1. #161
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    Quote Originally Posted by TXBob View Post
    ...I've never heard of one exploding for injury either.
    Colloquially referred to as a "kaboom," abbreviated to "Kb," and while injuries don't always result, they certainly do happen. They're also not common, but worst-case scenarios rarely are.

    It's pretty out of the ordinary for an item, condition, or event to get it's own nickname if it doesn't exist.
    Contractor scum, AAV

  2. #162
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    That is the point of the Failure Mode Analysis. For me its fairly easy. When my parts fail they don't cause injury.
    I've heard of KaBooms, but mostly for Glocks/Handguns/etc... I'm not trying to downplay, I really just don't have the info--but I bet these companies do!

    The important thing is there are 2 areas to be explored: (1) Failure rate and (2) Failure Mode. Just because you have a low failure rate, if your failure mode is catastrophic you have to be much much tighter on your failure rate.

    That's why I added my caution in there about how the parts fail and what they do cause. If it can be shown that a failure, even a single one would cause serious injury, well then test every part. Airline failure parts are 100X less (or more) than what I have, and yet I get away with sampling all the time. They can't even have a single failure and are X-raying parts even after they leave the factory.

    If you are out a $300 barrel or $1000 rifle, that's one thing.

    Lose a hand or an eye (or a life) that's another. That's why it is important to understand what happens if a barrel passes on that would have been caught. I'm just not familiar enough to say what would happen. Sounds like a few people here are so feel free to comment. As I said, playing a bit of devil's advocate. The more I study this the more I'm not liking batch testing.

    Failure rates in airlines are around PPM and they still test every one. Like I said, 1 part fails and you have death and destruction. The same could be said for a rifle. You won't have 100 dead, but 1 injury is enough to get lawyers involved.
    Last edited by TXBob; 03-20-11 at 15:28.

  3. #163
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    Rob,

    I am very grateful for the first two versions of the chart. Two immediate reasons come to mind:

    My first AR was NOT very good quality. I basically didn't know what I didn't know. The chart at least put some things in context, and EXPLAINED in cold hard facts, why one brand might be better quality, and the features that make up a good fighting carbine. The explanations are invaluable.

    Second, I have turned SEVERAL people on to this site. Right when they say "I'm going to buy a brand x because its as good as any of the others". I tell them to hold on a minute I tell them about this site and the wealth of knowledge from people who know. And the chart. To a man they have all come back to me after reaing here for awhile and studying the chart, and thank me for preventing them from making a big purchasing mistake (for what the carbine's intended purpose was). The chart is valuable, and it helps a lot of people that otherwise wouldn't understand WHY those features are important.

  4. #164
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    Hi Bob!

    About me: I too have several years' QA experience, and have taught college-level statistics.

    I can't agree with you. You need to do a LOT of batch testing in order for the numbers to be relevant. I worked in a battery plant, and tested x number of plates per shift. Critical aspects tested were thickness, lug location, weights, height, etc. We had no choice BUT to batch test - as each shift was producing well over a hundred thousand plates, it would have been impossible to check every plate. Enough testing ended up giving us solid stats.

    With barrel and bolt production numbers as low as they are, there's simply no reason *not* to HP/MP test each unit. The fact that some companies do test 100% without what I'd consider a significant cost impact supports this.

    Cost - as of now:

    Bushmaster bolt $56
    BCM bolt $69

    $13 difference isn't significant in this case - I'd pay that all day long for peace of mind.

    (I tried to find a comparable item as regards to barrels, but couldn't - I'd have had to compare complete Uppers, and that'd have ruined the comparison.)
    Last edited by The Cat; 03-20-11 at 15:35.
    Quote Originally Posted by MistWolf View Post
    A discussion involving the gayest lubrication, pinkies, Popsicles, hammering balls and dripping guns, all in the same thread...
    Quote Originally Posted by JSantoro View Post
    I like living a life in which beer is an appetizer, the floor is just another shelf, and the world is my urinal.

  5. #165
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    Guys, I'm not personally advocating for batch testing. Just saying a case can be made for it--no judgment on whether it SHOULD be done. I don't produce barrels and bolts, so I don't know the numbers produced, the failure modes, or the failure rates.

    But my point was for those companies that do, they should be able to provide that info and then we can take a look at it. Getting them to release it may be tricky--no one likes to release that kind of info. But until you look at the data, no one can sit here and say "Well I think the number of part xxx is this rate"

    Sorry it's a pet peeve of mine. I'm not paid to think or guess about data. I'm paid to know.

    The failure rate for N number of parts was X
    Only then can you explore sampling.
    Last edited by TXBob; 03-20-11 at 15:47.

  6. #166
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    Quote Originally Posted by TXBob View Post
    I'm not paid to think or guess about data. I'm paid to know.
    With 100% testing, you *will* know.
    Quote Originally Posted by MistWolf View Post
    A discussion involving the gayest lubrication, pinkies, Popsicles, hammering balls and dripping guns, all in the same thread...
    Quote Originally Posted by JSantoro View Post
    I like living a life in which beer is an appetizer, the floor is just another shelf, and the world is my urinal.

  7. #167
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    Quote Originally Posted by The Cat View Post
    With 100% testing, you *will* know.
    Then why does your company sample?

    I'm not trying to say it is ineffective to test every parts. I would like to know if we can get the data for companies that don't AND WHY THEY MADE THAT DECISION. It may be justified, it may not. We can argue about whether it is or not all day but 1 thing would settle that argument--their data.
    That's all. Armchair judgments of industries neither of us work in, aren't helpful.

    Its not a knock that a company tests every part. But if companies can show that the failure modes and rates of batch tested part are acceptable for a lower cost, that is valuable information.

    All I want is the data rather than a snap judgement good/bad. Yes on the surface, testing every part is a safe default setting. But there are conditions where it may not be. Very specific and definable ones.
    Last edited by TXBob; 03-20-11 at 16:10.

  8. #168
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    Quote Originally Posted by TXBob View Post
    Then why does your company sample?
    Because, as I stated in an earlier post, it is physically impossible to check over 100,000 plates in one shift.

    That's why the entire field of statistics exists - to sample a few in order to draw conclusions about the whole.

    My point was, and is, that there's simply no need for batch testing in the barrel and bolt industry - companies 100% test every day, again, without significant cost increase.
    Quote Originally Posted by MistWolf View Post
    A discussion involving the gayest lubrication, pinkies, Popsicles, hammering balls and dripping guns, all in the same thread...
    Quote Originally Posted by JSantoro View Post
    I like living a life in which beer is an appetizer, the floor is just another shelf, and the world is my urinal.

  9. #169
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    My point entirely, you're assuming the volume is low. All I'm asking is for the actual data. (I'm nutty like that). Also What works for a high volume mfg, may not work for a custom shop due to numbers.

    What's significant cost increase?
    How many do they test?
    What are the rates?

    How many barrels does Colt produce? Noveske? Kreiger?

    Yes, 100% testing is better.
    Is it necessary? Is it cost effective? Nothing comes for free.

    $1?
    $10?
    $100?

    Your and my final decision may even disagree, but WE WILL HAVE THE DATA TO MAKE THE CHOICE.

  10. #170
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    Speaking as the CUSTOMER - I don't care two shits about in-house QA numbers. All *I* want to know is, has my bolt and barrel been inspected properly? The Chart tells me who does it 100%, and that data tells me where I need to buy my gear.

    I'm not *assuming* anything. I'm certain Colt has a pretty high volume, and they are able to 100% test. BCM may not have the volume, and *they* can 100% test. And so on. There again, a company like BM has no excuse.

    'Custom shops'? Not sure what you mean by that - but if someone is paying the bucks for a custom rifle, then they expect them to use premium components... so that approach holds no water.

    I define $13 as being NOT a significant cost increase when it comes to testing one of the two most critical parts of the entire weapon. That's just a little more than the cost of a box of ammo, and any reasonable person would agree that that is money well-spent. So yes, it's necessary and it's cost-effective.
    Last edited by The Cat; 03-20-11 at 17:01.
    Quote Originally Posted by MistWolf View Post
    A discussion involving the gayest lubrication, pinkies, Popsicles, hammering balls and dripping guns, all in the same thread...
    Quote Originally Posted by JSantoro View Post
    I like living a life in which beer is an appetizer, the floor is just another shelf, and the world is my urinal.

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