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Thread: Barrels 101

  1. #11
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    Are all calibers "bored/drilled" as a single pass operation? Seems some of the larger calibers require a lot of material removal which would lead to some issues.

    Can you expand on how the chips are removed during the actual machining?

    I have a lot of questions but will contain myself.

    Thanks for the post.


    Bomber

  2. #12
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    Quote Originally Posted by Hardgear, LLC
    Are all calibers "bored/drilled" as a single pass operation? Seems some of the larger calibers require a lot of material removal which would lead to some issues.

    Can you expand on how the chips are removed during the actual machining?

    I have a lot of questions but will contain myself.

    Thanks for the post.


    Bomber
    In all of what I know, it is a single pass for each step; the drilling, reaming and sometimes honing. The drills are pretty unique... if you take a look at this site you will get a better idea of how the drills work...

    The drills have high pressure lube/cooling fluid injected that flushes the material out -- the most common inject the fluid down the center of the drill and material is evacuated down a deep "V" groove that runs the length of the shank... some drills evacuate down the center, and force the fluid in from around the outside.
    The sun will rise tomorrow; it’s your attendance of the event that is uncertain.

    Gun Plumber at Designated Hitter, pet protector and independent consultant to various irresponsible companies

  3. #13
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    When are you going to discuss barrel life? It would be nice if you explained how barrels burn out at the throat regardless of the rifling, which kills accuracy at longer ranges. The barrel with 7K rounds that shoots 4 MOA at 500yds, may still shoot 1 MOA at 100yds.
    100 yards is farther than a lot of people think.

    A good barrel is a good barrel, and if used for something other than achieving the highest X count, the point of diminishing returns is something too many folks choose to ignore.

    I don’t know, my glasses are yellow.

  4. #14
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    What color is your mustache?

  5. #15
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    Quote Originally Posted by bigbore
    When are you going to discuss barrel life? It would be nice if you explained how barrels burn out at the throat regardless of the rifling, which kills accuracy at longer ranges. The barrel with 7K rounds that shoots 4 MOA at 500yds, may still shoot 1 MOA at 100yds.
    100 yards is farther than a lot of people think.

    A good barrel is a good barrel, and if used for something other than achieving the highest X count, the point of diminishing returns is something too many folks choose to ignore.

    I don’t know, my glasses are yellow.
    I intend to add that...

    Of course the throat errosion is what kills a barrel (usually) and as you know the AR barrel can not be set back, and you are right on that accuracy figures can not be extended over range with any certainty.

    I agree with your last statement completely... I like to use a simple (hypothetical) math formula to demonstarte the point better: Just say that formula is, that to reduce your group size by half, will double the cost of the barrel -- all is well and good to say "I will take the 150 dollar barrel that shoots 1.5 inch groups over the 75 dollar barrel that shoots 3.0 groups." It is even understandable to say "Better yet, let me get the 300 dollar barrel that shoots 0.75 inch groups, instead of the 150 dollar one." But it starts to get tough to rationalize saying "Actually, I want the 600 dollar barrel that shoots 0.38 inch groups...."

    But as they say in the motorsports world... Speed cost money, how fast do you want to go?

    I was just at Frys this morning looking for a new DVD player and I hit the computer section -- they have a big display for the new Intel processor. That processor costs like five times what the one I have in this computer cost... I talked to the guy at the display a little and asked him "who really needs that?" He told me that outside of a few professionals doing very serious CGI and stuff, no one really needs it. So, I asked him "why would anyone pay that price for it then?" -- Just to say that they have it... his opinion of course, but hard to argue; heck, you can get a tshirt that says you are the owner of the latest computer processor.
    The sun will rise tomorrow; it’s your attendance of the event that is uncertain.

    Gun Plumber at Designated Hitter, pet protector and independent consultant to various irresponsible companies

  6. #16
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    Can you explain copper fouling to me like I'm 4 years old?

    My 11.5" is a SS Wilson/RRA barrel that I cut down, plugged the gas port, and drilled another 1" forward. Its been host to a few different suppressors, been through 1 Hackathorn class, and lots of blasting with a fair amount of full auto mixed in. I just passed the 5K round mark a few weeks ago. To see how it was shooting I put up a target at 100yds, and put 5 75gr TAP rounds down range. 4 of those 5 shots can be covered with a nickel. It still shoots.

    Its a well cared for barrel as far as carbines go. I clean it after every trip to the range. Hoppes #9, wet patch dry patch. I dont use a brush.

    For the first time, I did the hoppes procedure, then shooters choice copper remover - wet patch dry patch. I lost count, but It took 45 minutes before the patches came out white instead of blue.

    With this being an "economy" barrel (will foul more), which still shot damn well, with all that copper, how much of a concern is copper fouling in a practical carbine?

  7. #17
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    Quote Originally Posted by bigbore
    Can you explain copper fouling to me like I'm 4 years old?
    I don't know if I can explain anything to anyone in those terms

    Nor do I think that I can share anything about barrel fouling that you do not already know, but here is what I do know. Jacket fouling is a result of two things, the first being the jacket material that is released from the bullet in the initial stage of the shot, this occurs as the "gases" are actually in a plasma state and heat the jacket to the point that copper is released into the plama state.

    This is a more like a plating really, it occurs in the very first part of the barrel throat and bore and is generally very uniform in deposition.

    After this, the more traditional form of fouling occurs as the gilding metal galls in the bore; these patches of built up copper cause differences in the friction that is applied to the bullet as it travels down the bore. This friction can "tear" at the bullet's jacket and deform the base of the bullet, causing it to be unstable in flight.

    Now, how often does it occur and at what point is it an issue? I have found that barrels are a lot like people in this matter; just like some people have a natural propensity to be artistic, athletic, or whatever... some barrels will foul more than others -- there is no hard and fast rule as to what make a barrel more or less likely to be a "fouler", but bore surface and consistant/correct bore diameter certainly play a big part in it.

    As you know, there are the odd occasions where a barrel can not go a half dozen shots without throwing rounds all over the place... a good cleaning and it is back for a few more rounds, but fouls out just as quickly -- I think the name for these is "lemon" or "junk"?

    And as you know, some rifles can go hundreds or thousands of rounds with little effect on accuracy from fouling -- when a shooter makes his first shot, it is called a Clean Cold Bore (CCB) shot, professional shooters even have seperate dope for this... oddly enough, the CCB shot is generally not the most "efficient" shot, as thin films of lubricants can increase the force needed to push that first shot and the cold bore is "tight" -- this CCB shot generally will have a higher recorded peak chamber pressure than the follow-up shot, I have known guys that even put a round in the ground before a patrol for a "fouling shot" (and other reasons).

    As stated, bore surface is a primary suspect in a fouler... lapping and plating are thought to be preventive measures and record books support this.

    To answer your question though, fouling is a concern if it is a problem (how is that for a cop out!) -- with most "practical" guns, fouling will reduce accuracy so little that it is not noticed... we can always blaim that one "flyer" on fouling though -- benchrest shooters can give themself ulcers worrying about it, but most of us don't have to worry that much, the potential for the group opening can still be covered by the illuminated dot in the optic sight...

    As for the "blue patches" as a litmus test for copper... that can be very deceiving, it takes very little copper to make those patches blue and a lot of that fouling resides in the corners of the rifling, where is is doing little harm.
    The sun will rise tomorrow; it’s your attendance of the event that is uncertain.

    Gun Plumber at Designated Hitter, pet protector and independent consultant to various irresponsible companies

  8. #18
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    I wonder if I can make a barrel out of kryptonite ?? That way I can fight evil powers across the universe ....

    All joking aside, GREAT POST KL, like always ...
    Brett W

    Elite Defense
    Vice President of Domestic Sales and Marketing


    FN Senior Manager of Assault Weapons - SCAR Program 2006-2010
    Former Troy Industries Inc Director of Operations 2003-2006

    Each Warrior wants to leave the mark of his will, his signature, on important acts he touches. This is not the voice of ego but of the human spirit, rising up and declaring that it has something to contribute to the solution of the hardest problems, no matter how vexing!
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  9. #19
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    Barrel break in procedure

    I know this is going to paint me as a noob, but I have to ask. I just built my first AR. This will not be my first time using the platform by any means, mind you. I have been isued probably 10-12 different AR variants over my time in the Army but none of these were NIB. The closest was the M4 that I was issued when I deployed to Iraq. As such I was never concerned with proper break in. For that matter I never remember in my time in the Army ever being told how to break in a new rifle. I am not sure if this is the best place to post this question but I figured that it being titles Barrels 101 that I would post it here. Thanks.

  10. #20
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    Quote Originally Posted by K.L. Davis View Post
    The most common stainless in use for AR barrels is 416, this steel is plentiful, not expensive and machines nearly as well as the carbon steels
    The statement in red is backwards. 416R is easier to machine than the chromoly steels.

    Great write up!
    Austin Nichols = Wild Turkey

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