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Posted: 5/9/2012 7:46:52 AM EDT
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First of all, I have read extensively on this forum (and others) about this, but I question whether or not barrel nut torque is really that big of a deal based on several observations:
1) The pressure from the cartridge is forcing the barrel toward your shoulder, not away from you. Am I wrong about this? 2) The torque range is pretty broad. 35-80 ft/lbs. 3) Shotguns. (I REALIZE THE CHAMBER PRESSURE IS MUCH LOWER) Shotgun barrels are attached simply by a hand-tightened cap. 4) Bushmaster ACR. If you watch the caliber change video you realize that the barrel is simply removed by a cam lever and a quarter twist. Why does any of this matter? 1) I was scared to death to screw up what should have been an easy task. 2) There is a LOT of conflicting info. For example, my midwest industries handguard came with instructions to "hand tighten" and align next gas port hole. Now for my questions: 1) Is it a safety issue or an equipment issue (don't want to crack the upper, etc.)? 2) Does anyone actually have experience with an upper assembly failing that can undoubtedly be attributed to over/under torqued barrel nut? I am open and willing to be correct should anyone provide facts to disprove any of my points. Thanks! |
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Quoted:
First of all, I have read extensively on this forum (and others) about this, but I question whether or not barrel nut torque is really that big of a deal based on several observations: 1) The pressure from the cartridge is forcing the barrel toward your shoulder, not away from you. Am I wrong about this? 2) The torque range is pretty broad. 35-80 ft/lbs. 3) Shotguns. (I REALIZE THE CHAMBER PRESSURE IS MUCH LOWER) Shotgun barrels are attached simply by a hand-tightened cap. 4) Bushmaster ACR. If you watch the caliber change video you realize that the barrel is simply removed by a cam lever and a quarter twist. Why does any of this matter? 1) I was scared to death to screw up what should have been an easy task. 2) There is a LOT of conflicting info. For example, my midwest industries handguard came with instructions to "hand tighten" and align next gas port hole. Now for my questions: 1) Is it a safety issue or an equipment issue (don't want to crack the upper, etc.)? 2) Does anyone actually have experience with an upper assembly failing that can undoubtedly be attributed to over/under torqued barrel nut? I am open and willing to be correct should anyone provide facts to disprove any of my points. Thanks! 1. It's 30 - 80 which can be important if you can get alignment in the mid-thirties. If you think the low number is 35 you apt to blow through your gift and end up breaking things trying to get to the next alignment. Broken Upper Shotgun comparison not valid. Bushhampster, MI float tube nut....have not used these. |
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Looks like your broken upper example comes from not using the proper equipment, not torque values.
Can you give some evidence that my shotgun comparison is not valid? This is what I am talking about... you just throw that out there like you're the expert that I am supposed to believe in the sea of 100,000 experts. I'm just making simple observations and asking questions so if my shotgun comparison is not valid, explain why. Thanks! |
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Quoted:
Looks like your broken upper example comes from not using the proper equipment, not torque values. Can you give some evidence that my shotgun comparison is not valid? This is what I am talking about... you just throw that out there like you're the expert that I am supposed to believe in the sea of 100,000 experts. I'm just making simple observations and asking questions so if my shotgun comparison is not valid, explain why. Thanks! Sounds like you have your mind made up. Run with it. |
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Quoted:
First of all, I have read extensively on this forum (and others) about this, but I question whether or not barrel nut torque is really that big of a deal based on several observations: "that big of a deal" in regards to what? safety? proper function? accuracy? probably not a safety issue. people have safely fired their rifles with hand-tight barrel nuts. kind of a deal for proper function - there's a very, very narrow range of angles off top dead center which will allow the bolt to enter the barrel extension, and the gas tube to enter the carrier key. major deal for accuracy with iron sights - the front sight is on the barrel, if the barrel can move, you'll have no repeatable zero. The barrel nut torque is specified by the manufacturers to keep the barrel tight and unmoving to the upper over the expected range of operating stresses induced by handling, and firing, and maybe buttstroking or bayonetting. If you've got a safequeen, you'll probably be fine with less torque on the barrel nut - but don't be surprised or act upset if it works loose on you from normal firing and handling stresses. Note that the gas tube will prevent it from just unscrewing itself, but that won't mean it couldn't be loose enough to let the barrel wiggle or cant a teensy bit during recoil. |
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ultimately the exact torque that you have to use to install a barrel is not that big of a deal.
if it's over 30 it should be tight enough where it won't ever move on it's own which could affect accuracy and function. if you go over 80 sometimes don't even have to go that high you can break your gear. There are several broken upper posts out there. Not that common installing a barrel more often removing. Over torqueing your barrel nut could result in breaking something when you remove it later or you gall the threads and it can work lose. |
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I think the barrel nut installation is more about being adequately lined up and adequately tightened at the same time.
If you take 100 average Joes, you'll likely end up with a good number of different types of people with different modes of thought. Example #1. When instructions say something like, "tighten nut well and make sure it lines up properly" you'll get more than several Joes that ask, "how tight"? OK, so the manufacturer says something like, "between X-X # of torque until it lines up". Now the manufacturer eliminated all the questions and created more of a standard for nut instillation to satisfy just about every Joe that exists. Example #2. Sometimes, but not always, you'll get a Joe that asks, "why between X-X # of torque, is that necessary? Can't I just tighten the nut well and make sure it lines up"? Sure, just don't over or under tighten it. Well that's kinda the category where this topic falls. See example #1, compare it to example #2 and decide which you prefer. Either go with what is recommended or just tighten it. The same can be asked when installing an optic in a scope mount. How tight should the screws be? Many manufacturers list a recommended torque. Either do it or don't. Can you under tighten them? Yes. Can you over tighten them? Yes. 1) I was scared to death to screw up what should have been an easy task. 2) There is a LOT of conflicting info. For example, my midwest industries handguard came with instructions to "hand tighten" and align next gas port hole. 1) Then just simply use a torque wrench like most recommend and don't sweat it. I believe you're over-thinking this. 2) Call and ask them this question, it's their product instructions. Are you considering using that product or are you just using that instance as an extreme opposite for this comparison? All kinds of other questions could be asked as well. Like for instance loktite. Many if not most will say, "don't use loktite on your barrel extension or barrel nut". Well there are highly respected manufacturers that use RED loktite on most every part installed. |
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