Archive for the 'AR-15s' Category

Gun News Daily has an interesting list of recommended AR-15 armorer’s tools, including Brownell’s armorer’s wrench, and others.

I’ve used a Magpul castle nut wrench before, and it’s very good.  The Starrett pin punch set looks interesting, and especially interesting is the Wheeler Engineering AR-15 armorer’s set.

Do any readers have good recommendations for others, or perhaps having worked with these, do you have preferred tools?  I know that Brownell’s has a full AR-15 armorer’s kit.

Shooting Illustrated.

Direct-impingement (DI) gas tubes—such as those used on most AR platforms—should be checked periodically to ensure the hardware that secures them is present and tightly fitted. If you can access that area, removing the roll pin (or screw) will allow you to inspect the forward end of the gas tube for any cracks where the pin passes through. This is not a frequent check, but it is worth doing anytime you remove a gas tube. Any cracking around the pin hole requires replacement of the tube. Remember to re-pin the gas tube after reinserting it into the block.

Gas tubes benefit from periodic internal cleaning, too. Short, large-diameter AK- and SKS-style gas tubes can be scrubbed out with an appropriately sized brush and solvent, then swabbed dry with a clean, lint-free rag. Ensure that the locking cam that holds your gas tube in place remains fully engaged when assembled and that the tube itself is not badly dented or misshapen.

AR-type tubes can be cleaned out with long, purpose-made pipe cleaners and some bore solvent or a .063- to .076-diameter spring wire. You can do this from inside the upper receiver, eliminating the excuse of not wanting to remove the gas tube. Judging by past comments I have received on this subject previously, the concept of cleaning gas tubes is taboo in some circles. As long as you do not stick something in there that will get stuck (like the end of a cotton swab) cleaning it out is both acceptable and recommended. Use a flashlight if the dark space scares you. Just clean it out and move along, little fella. Check gas-tube ends for damage from moving parts, such as bolt-carrier keys or locking cams. Replace the tube if it has been beaten up in this area.

I’ve never cleaned gas tubes, and I’d like some gunsmiths to weigh in with their experience with this.  Is this really necessary?  The gas velocity in the tube is extremely high.

What does Mr. Stephen Bayezes and a pregnant woman in Florida have in common?

Here’s another report.

“They came in heavily hooded and masked,” homeowner Jeremy King told Bay News 9. “As soon as they had got the back door opened, they had a pistol on me and was grabbing my 11-year-old daughter.”

That’s when they began pistol-whipping him and demanding money, King said.

“I’ve got a fractured eye socket, a fractured sinus cavity, a concussion, 20 stitches and three staples in my head,” he said, outside his home about 20 miles southeast of Tampa. “I took a severe beating.”

King’s wife, who’s 8 months pregnant, peeked out of a back bedroom during the commotion to see what was going on, according to King.

One of the men saw her and fired off a shot, he said. She closed the door and grabbed the family’s AR-15.

I’ll decide how best to defend home and hearth, thank you very much.

Cheaper than Dirt.

If it’s not USGI-pattern (that has 20 “scallops” around its circumference), most provide a head to match their nut. But I’ve seen a few I just had to wing it with, which often meant resorting to a large adjustable wrench to fit the wrench flats on the nut.

To fit the drive, ask for a “crows-foot” attachment at an auto parts store.

If your barrel nut is USGI-pattern, get a wrench head that fits over and into as much of the nut circumference as you can. My favorites give 360-degree contact, but most are half that (or less). And make sure the doggone thing is securely fitting into those scallops!

I hold in against the wrench head when I work the wrench handle to keep the head from slipping.

Longer wrench handles are better than shorter ones. Longer makes it easier to make those often-necessary small-but-high-effort nudges easier to feel, and to initiate. I use both a torque wrench and a breaker bar, and the latter is because of the next important item.

Anti-seize! This auto-parts store item is a critical component.  It’s a copper-based lubricant intended exactly for what we’re doing here—it prevents galling.

Galling is abrasive wear from the friction that occurs when metals that are compressed against one another are put into motion.

If the compressive forces are high enough between the surfaces (and they sure can be), the friction can create heat sufficient to weld the materials together and that then removes material from one surface and places it onto the other. Not good!

To get the operation going, clean off all associated surfaces (inside of the upper and outside of the barrel extension). Slip the barrel extension into the upper (there’s a pin on the extension and a notch in the upper that line up).

Put an even coat of anti-seize around the circumference of the upper threads (I use a flat artist’s brush) and thread on the barrel nut. Using something other than a torque wrench, tighten the nut down firmly—give it a good pull—and back it off.

Repeat that three or four more times: tighten it to snug-plus and back it off.

Why?

Because that helps mate the surfaces by facing down any small imperfections (which will usually be on the upper). The anti-seize allows this tactic.

The tighten/loosen procedure is compressing tiny bits of metal, and the lube is preventing galling, as well as make it easier to loosen.

Now for more about that “alignment with the gas tube receptacle in the upper receiver. ” That is absolutely critical, or it is if you want your AR-15 to shoot as well as it can.

With a USGI-pattern nut, that means one of the scallops has to be dead center in the gas tube receptacle in the upper so the gas tube isn’t touching the nut—not even a little bit. With another style barrel nut, it might not mean a thing.

The point is that if there is an opening on the nut that should align with the gas tube receptacle, it has to align!

That is now when and how the gas tube alignment tool really helps. Remove the bolt from the bolt carrier group, insert the tool in the carrier key, and slip it into the upper. There should be a gap 360-degrees around the tube. It’s a tiny gap, but it’s a gap.

Ultimately, final check it with the gas tube itself, and the test then is that the gas tube should rattle—move freely all directions.

This isn’t an evolution I’ve performed.  I’d like to think I could watch before doing it.

What was that you said, controller?  I didn’t hear you.  Speak more plainly.