Experienced AR builders know that there may be a few ways to achieve a particular task when building a rifle. We have our preferred methods, rituals, and we're all entitled to our reasons for our methods.
Because this is a site dedicated to building AR-15s, I feel it is important that we encourage diversity of method when building rifles, because that is how we learn. I also feel it is important to identify bad practices, and warn the inexperienced to avoid them
I love my wife, because she indulges some of my hobbies and habits. On several occasions, she shows up from a shopping trip with a gun magazine just because she thought I'd appreciate it. Her success rate is hit-or-miss, but it's great to have a random gun magazine arrive.
A few days ago, my wife came home with a "Guns & Ammo AR-15" magazine. I'd like to give a date for this issue, but it only has a "Display until" date (February 2017). She knows that after building 5 rifles, this AR-15 bug isn't going away. She says things like "I like walking around the house and seeing random gun related stuff. Pile of rifle cases in the corner of the living room, dresser drawer full of handgun pouches, barrel nut sitting on the counter. I know we're more prepared than most."
I knew something was weird when the editor wrote "Now that summer is here..." It's almost like the magazine is half advertisement, half rejected articles.
One article I was particularly interested in was about "Barrel Installation". Now, I'm not a novice. I may not have the experience of our gunsmith members - but after building 5 rifles, I've learned what it takes to install a barrel and align a gas tube.
My first build had a serious barrel/receiver alignment issue and after speaking with a few more experienced builders, I learned that the barrel interface might not be square and that there is a tool designed to resolve that issue. After learning that lesson, I lap every upper receiver and as a result I have built some very accurate rifles.
Another trick I learned from more experienced builders was how to align the gas tube. Depending on the barrel nut, there is a target torque range - but for the purpose of this article, I'm going to use the standard steel barrel nut torque range, 30 - 80 ft-lb. I was taught to tighten to 30 ft-lb 3 times, then once at 30 ft-lb on the third attempt - increase the torque setting to 60 ft-lb and tighten while inserting the gas tube. If you make it to 60, increase to 70, and then 80 until the gas tube slips into the receiver. Small moves, and when alignment happens - the gas tube slips right in. After the first time, it becomes second nature.
Then I read this Guns & Ammo article. It's this article that gives me an indication about why so many people have malfunctions. Because I don't want to cause a copyright issue - I'm going to only post one photo from the magazine for critique.
"It looks crude, but you align a slightly-not-right gas tube with a screwdriver. Shove it in, twist and bend to fit."
I couldn't believe what I was reading. They actually suggest bending the gas tube with a screwdriver to align it. If the gas tube isn't straight inside of the receiver - the gas tube isn't aligned through the barrel nut and things aren't ever going to be right.
Without proper alignment, a bent gas tube can cause many issues. First, it may bind in the BCG gas key and prevent proper cycling. It could also prevent the BCG from returning home and keep the bolt lugs from engaging. If it crashes into the gas key it may damage the key and/or the gas tube. A damaged gas tube may not allow enough gas to reach the key and cause a short-cycle condition.
In short, one tiny shortcut can cause a number of malfunctions. And this bad information is being perpetuated in one of the most widely circulated gun magazines out there.