Barrel & Upper Work

Some Tools Are Essential For Assembly.

There is a huge interest in folks wanting to assemble their own AR-15s. I characterize the efforts as somewhere between changing a lightbulb and installing a garbage disposal. Depends, of course, on the job at hand. To build an AR-15 you’ll need to install a barrel. That would be a long article, so here I’ll take a look at the tools you need for this project. As with any kind of mechanical endeavor, tools really matter to your success.

A good vise is absolutely necessary. You’ll need a heavy-duty model with at least a 4-inch jaw opening to hold things like receiver blocks and fixtures and barrels. Do not scrimp on the main vise.

My favorite is the Brownells Multi-Vise. This truly well-engineered tool is worth its cost. It can easily swivel and allows for vertical or horizontal jaw orientation. Again, you might not think it’s worth its cost until a lower quality vise lets you down. Of course, Brownells has a custom-fit set of pad inserts available for it too, and those are recommended.

The most important tool in your shop is a quality vise.
Without one, you’ll start with a handicap.

Clamps And Wrenches

To do any barreling work, you’ll need a means to hold the upper receiver securely, and without damage. Receiver blocks come in two essential formats. There are blocks that fit into the upper, and that style is my preference. The one I like best uses takedown pins so it is, in effect, like clamping the lower with the vise. Derrick Martin gets credit from me for this invention. Others are “clam-shell” parts that encase the upper and also fill the space where the bolt carrier normally occupies. There’s really no difference in how well they work.

The big difference, however, and pay close attention, is that the clamshell-style blocks are a skin-fit to an A2-configuration upper, whether it’s a flattop or carry-handle. That’s all they’ll work with. If you need to hold an upper that’s dimensionally different, such as one of the DPMS “competition” style uppers, and other unique styles, they won’t work at all.

Holding the barrel itself, normally using a pair of barrel vise-jaw inserts, is a popular way to secure an upper, but I so-o-o do not recommend it. The note against holding the barrel and for securing the upper is that the indexing pin on the barrel extension that fits into the upper can lever against its slot when the barrel, not the upper receiver, is held in place. This can elongate the slot. Barrel clamping block sets are numerous and it’s hard to find any that actually work all that well.

This is especially true if you’re installing a barrel that’s even a little different dimensionally than issue-spec standards (which is what the vise inserts are engineered around). Rosin can help stiffen the grip. It will take a good deal of pressure to secure a barrel from slipping when an inordinate amount of pressure has to be applied to a barrel nut to align a stubborn gas tube hole. Don’t worry, by the way, you’re not going to bend or crush a barrel. I don’t like clamping the barrel because of what was just said. It also mars the fool out of them, no matter what I’ve tried.

I do, though, think such appliances are handy for installing, or removing, muzzle attachments and securing a barrel for a chamber polish or for thorough cleaning. Especially in an op like removing a flash-suppressor, I prefer clamping the barrel itself rather than using an upper-receiver clamp to secure the works. There’s a lot of leverage working all the way out at the end of the barrel and clamping the barrel itself takes that advantage away from what might otherwise be directed against the upper receiver.

Holding the lower is painless and downright convenient with one of the blocks that substitutes for a magazine. There’s little stress ever levered against a lower that in any way compares to that raged against an upper during a barrel or fore-end tube installation. They are also daggone handy for cleaning, sight installations, and general maintenance work. I have one clamped in a vise most all the time.

To install a barrel, any barrel using virtually any retention means (meaning free-float tube or not), you’ll need a specialty barrel nut wrench.

The “armorer’s combo-tool” standard has three prongs that engage the scallops in a barrel nut. This will work with any barrel nut arrangement that’s configured like a standard nut, including those on most free-float tubes. I prefer the “full-round” style that engages each and every scallop. This style wrench, however, has to be able to fit over the muzzle and be brought back to the barrel nut, so can’t be used if installing a barrel that already has the front sight housing or handguard cap affixed.

I do not recommend purchasing one of the multi-purpose tools that has its own handle and is a self-contained tool. (By the way, the reason I’m referring to these as “multi-tools” is that they have cutouts that fit, sort of, the receiver extension and flash suppressor nut.) The variety of barrel nut wrench you need has an attachment for a 1/2-inch drive, into which goes a wrench handle, and now we’ll talk about those.

Never, ever vise-up an upper without either of these devices. The “clamshell” type (above) is the most popular and is a skin-fit to an A2 upper with or without its charging handle. Glen prefers a style that fits exactly inside the upper receiver (below). The upper receiver can’t move using this block. The limitation of the clamshell style is that it only fits an A2, not any of the “other” configuration uppers, such as the newer billet-made uppers. In other words, the clamshells works off the exterior and the insert works off the interior. The interiors don’t change.

Torque Wrench

A breaker bar and torque wrench are important tools, especially for those inexperienced with barrel installations. If you don’t have a torque wrench then you’re guessing, but after a few installations you’ll be guessing on the safe side of error. The reason for the breaker bar is because rumor has it that a torque wrench should only be a one-direction tool: it’s only used to tighten, never loosen. I couldn’t really confirm that rumor, even after asking a few race mechanics, but let’s assume it’s true.

These tools can come from any good mechanic’s supply. I like torque wrenches with longer handles because sometimes the amount of force needed for a barrel installation gets on up there and the longer handle makes subtle shifts toward tight easier to control. The breaker bar is therefore only needed to loosen this nut.

As mentioned, the combination tools have additional cutouts to fit the receiver extension tube and muzzlebrake nut, but the fit is usually poor. It’s far preferable to have handy a good quality adjustable wrench, or better still, open-end wrenches that are correctly sized for these fasteners.

Information in this article was adapted from The Competitive AR15: Builders Guide, published by Zediker Publishing. Glen is a card-carrying NRA High Master earned using an AR-15 service rifle. For more information, including many downloads, check

Barrel clamps are not to be used for installing barrels, says Glen, but do come in handy when it’s necessary to work on the barrel itself. Rosin helps increase the grip if necessary. Always clamp the “fat” part of the barrel.

Here’s a barrel nut wrench (above), when Glen can use it. This grips the barrel nut scallops full around but only works when it can be slipped over the muzzle. When a front sight is already mounted, then something with an open end is necessary such as the “standard” armorer’s wrench (below). There are others, but the wrench needs the 1/2-inch drive cutout for use with a breaker bar and torque wrench.

Accuracy Speaks Inc.
7445 E. Diamond Ave.
Mesa, AZ 85208
(480) 748-9061

Brownells Inc.
200 S. Front St.
Montezuma, IA 50171
(800) 741-0015

By Glen Zediker

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