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Posted: 8/28/2011 3:14:57 PM EDT
| What tools, fixtures, and methods do you guys all used to insure proper gas tube alignment when building a upper. |
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Do you mean putting the gas tube in the FSB or gas block, or lining the gas block up with the barrel? Putting the gas tube in for me it always seems to fit in tight enough that it doesnt really move around. I start the roll pin in just a little bit, and it is pretty simple. Putting a gas block you it is easy enough to eye ball. If the barrel is correctly dimpled the block will be fine. I have a set of roll pin holders that make putting together ARs much easier.
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I was eyeballing them. Sometimes it took a few tries to get it perfect. Line it up, look, and test fit the carrier without the bolt or charging handle to make sure the gas key engages without flexing the portion of the tube that is in the upper. If the key pushed the tube to either side while sliding the carrier back and forth I'd adjust the nut. You are not supposed to loosen the nut, so it's better to start with it slightly behind rather than forward (less torque rather than more torque) so you don't go past the groove in the nut.
I bought a Schuster Barrel Nut Indexing Tool and it pretty much gets it right the first time. You can also use a piece of old gas tube, proper size drill bit or rod to do the same thing. It's not a necessary tool, but makes the process easier. The gauge will not fit unless the nut and receiver are in alignment. |
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Well in my first post I managed to not answer your question at all, but I have always been able to eyeball barrel nut alignment. Just make sure it is in spec and get it to where it needs to be. Tool wise I just use a vise block and a barrel wrench, and have never had issues with it.
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Quoted:
I was eyeballing them. Sometimes it took a few tries to get it perfect. Line it up, look, and test fit the carrier without the bolt or charging handle to make sure the gas key engages without flexing the portion of the tube that is in the upper. If the key pushed the tube to either side while sliding the carrier back and forth I'd adjust the nut. You are not supposed to loosen the nut, so it's better to start with it slightly behind rather than forward (less torque rather than more torque) so you don't go past the groove in the nut. I bought a Schuster Barrel Nut Indexing Tool and it pretty much gets it right the first time. You can also use a piece of old gas tube, proper size drill bit or rod to do the same thing. It's not a necessary tool, but makes the process easier. The gauge will not fit unless the nut and receiver are in alignment. I am not saying your method will not work, but it is not what I was taught in the Army. One aligns the nut so it is centered. Once the gas tube is installed you tweak it (read bend it) until it is aligned with the key. |
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Quoted:
Quoted:
I was eyeballing them. Sometimes it took a few tries to get it perfect. Line it up, look, and test fit the carrier without the bolt or charging handle to make sure the gas key engages without flexing the portion of the tube that is in the upper. If the key pushed the tube to either side while sliding the carrier back and forth I'd adjust the nut. You are not supposed to loosen the nut, so it's better to start with it slightly behind rather than forward (less torque rather than more torque) so you don't go past the groove in the nut. I bought a Schuster Barrel Nut Indexing Tool and it pretty much gets it right the first time. You can also use a piece of old gas tube, proper size drill bit or rod to do the same thing. It's not a necessary tool, but makes the process easier. The gauge will not fit unless the nut and receiver are in alignment. I am not saying your method will not work, but it is not what I was taught in the Army. One aligns the nut so it is centered. Once the gas tube is installed you tweak it (read bend it) until it is aligned with the key. It's the same thing. Achieve minimum torque and align the next groove so it is centered. That is visual. Verify it through a check (gauge, drill bit as Russ mentioned, empty carrier, old piece of gas tube). If it is off, make any necessary adjustments to the nut. Once the barrel is installed properly any final adjustments can be done by bending the tube slightly. |
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I read somewhere that you get it close, and then just grind the barrel nut slot until the tube has enough clearance. That's the lazy way out. I'd be pissed if I pulled the handguards off of a factory rifle and saw that the barrel nut had been ground on to fit. |
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Quoted:
Quoted:
Quoted:
I was eyeballing them. Sometimes it took a few tries to get it perfect. Line it up, look, and test fit the carrier without the bolt or charging handle to make sure the gas key engages without flexing the portion of the tube that is in the upper. If the key pushed the tube to either side while sliding the carrier back and forth I'd adjust the nut. You are not supposed to loosen the nut, so it's better to start with it slightly behind rather than forward (less torque rather than more torque) so you don't go past the groove in the nut. I bought a Schuster Barrel Nut Indexing Tool and it pretty much gets it right the first time. You can also use a piece of old gas tube, proper size drill bit or rod to do the same thing. It's not a necessary tool, but makes the process easier. The gauge will not fit unless the nut and receiver are in alignment. I am not saying your method will not work, but it is not what I was taught in the Army. One aligns the nut so it is centered. Once the gas tube is installed you tweak it (read bend it) until it is aligned with the key. It's the same thing. Achieve minimum torque and align the next groove so it is centered. That is visual. Verify it through a check (gauge, drill bit as Russ mentioned, empty carrier, old piece of gas tube). If it is off, make any necessary adjustments to the nut. Once the barrel is installed properly any final adjustments can be done by bending the tube slightly. I took what you said earlier as saying you would adjust the nut to line up the gas tube with the key. |
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I read somewhere that you get it close, and then just grind the barrel nut slot until the tube has enough clearance. That's the lazy way out. I'd be pissed if I pulled the handguards off of a factory rifle and saw that the barrel nut had been ground on to fit. I have to disagree. It would take longer, in a WECSOG sort of way. I'd sent it back. If the barrel nut was so hard to install, what else got eff'ed up? |
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I read somewhere that you get it close, and then just grind the barrel nut slot until the tube has enough clearance. That's the lazy way out. I'd be pissed if I pulled the handguards off of a factory rifle and saw that the barrel nut had been ground on to fit. +1000 There is no telling what else someone who would cut a corner like that would do. |
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