Removing Pinned And Welded Muzzle Devices With Basic Tools

Most gun enthusiasts remember the dark days of the early 1990s, when bills such as the "Violent Crime Control and Law Enforcement Act of 1994", better known as the Assault Weapons Ban were passed into law.

Fortunately, a large chunk of the AWB’s nonsensical provisions were sunset into the pages of history in 2004, however, one remnant of the AWB left many semi-automatic rifles, ARs in particular, floating around with muzzle brakes and flash suppressors (hereafter referred to jointly as muzzle devices) that have been pinned and welded in place, as per BATFE regulations. Recently I’ve had several customers bring ARstyle rifles in for work that required the removal of such muzzle devices.

Since my mill and lathe still reside in a friend’s warehouse several states away, removing these devices with basic tools was my only option short of replacing otherwise good barrels altogether. The most common job requiring the removal of an AR’s muzzle device is free floating the barrel with a fully-round free float tube. Second to that is swapping a standard front sight assembly (FSA) with a lower profile gas block.

In most cases, either action requires the FSA or gas block to be removed from the barrel via the muzzle. Removing a pinned and welded muzzle device with an end mill is pretty straightforward but when heavy equipment is not available, basic hand tools, a high speed rotary cutter and some patience are all that are needed to accomplish this task. Parkerized muzzle devices normally show a contrasted spot at the pin location due to the different device and weld metals.

If pins are not directly opposite, only one can be used to locate a cut. The most common BATFE-approved method of pinning and welding a muzzle device requires drilling through the rear portion of the device into the threaded portion of the muzzle. Short sections of steel rod are interference fit into the holes and welded over. The welds are then fi led, ground or milled down to match the muzzle device’s outer profile. Finally, the muzzle device is refinished.

The pins used in this method will destroy muzzle threads if force is used to break the muzzle device free while unscrewing it, as more than one AR owner has learned the hard way. A word of caution before proceeding. Consult all applicable local and state laws before removing a pinned and welded muzzle device. Some states may have provisions in their laws that prohibit removable muzzle brakes/flash suppressors or threaded muzzles.

You should also determine whether or not you have a short barreled rifle (SBR) as defined under the National Firearms Act of 1934. Under NFA rules, a barrel that is less than sixteen inches or an overall rifle length of less than twenty six inches places along gun into the SBR category and must be registered as such, unless a muzzle device is permanently attached to bring the rifle In this case I’ve cut away the section of the device that was in line with my cut location.

While you could also leave this section intact and extend your cut line the full length of the muzzle device, Ifi nd this method is faster and prolongs the life of the cutoff wheel. In this example I was working my way down to 11/64", with a marking at 10/64" to warn me that I’m getting close. to greater than these mandated SBR lengths.

If your customer brought you a registered SBR, BATFE guidelines should allow you to perform routine gunsmith services on it but you must be aware of the appropriate regulations and stay in compliance with all NFA rules. In the event the rifle has a barrel shorter than sixteen inches and a pinned/welded

brake that brings barrel length to over that, unless you have a Class II Special Occupational Tax stamp allowing you to manufacture NFA firearms, you’ll either need to replace the muzzle device with another that brings the barrel to a legal length or replace the barrel assembly with a longer one. Identifi cation Job number one when preparing to remove a muzzle device is to determine whether or not it was pinned and welded in the first place. Several indicators help this process.

If the rifle is a semi-auto with a removable magazine and is known to have been sold during the 1994 to 2004 AWB window, there is a good chance the muzzle device is pinned and welded. If the carbine is not registered as an NFA firearm and the barrel is shorter than sixteen inches without the muzzle device’s length figured in, the muzzle device brings length to a full sixteen inches it should be pinned and welded.

If I suspect a pinned and welded job I move on to visual inspection using a good light looking for the telltale circular discoloration that normally indicates such a job. They’re most often encountered on the opposite sides of a muzzle device but occasionally I come across single pinned devices. I Cut carefully to avoid contact with the barrel once through the baffle. use the same process for a single or double pinned muzzle device.

If you see no visual indications of pins or welds, apply heat to the muzzle device to loosen up any thread locking compound before carefully trying to loosen it. If it won’t budge after applying moderate loosening pressure, stop. Unless you plan to scrap and replace the barrel, proceed with caution until you confirm or deny whether or not the muzzle device is pinned and welded.

You not only stand to damage barrel threads but excessive torque on a pinned and welded muzzle device could result in damage to the aluminum upper receiver caused by the barrel extension’s steel index pin breaking free of the index pin slot. Starting Points Once a pinned and welded job is confirmed, I use a combination of

Once the crack is visible, no further cutting is necessary and it’s relatively easy to split the device away. The crush washer just to the rear of the muzzle device provided a buffer for the cutoff wheel, preventing barrel damage. tools to split the muzzle device into halves by cutting down close to the barrel’s muzzle threads from both sides. I use the pin locations as my guide to begin cutting.

I’ve found that locating just off one side of each pin allows the cuts to free the muzzle device from the pins once enough metal has been cut away. Muzzle devices with two pins tend to be pinned on opposite sides which facilitates removal nicely. If your cuts don’t directly oppose each other, unequal pieces of the muzzle device will be cut.

The smaller of the two will fall away easily once cut through, while the larger piece may still encircle enough of the barrel threads that it cannot be removed without another complete cut to further section it. That will add another 1/3 to your labor time. The Cuts Before beginning my cuts I position the barrel in a padded vice horizontally so that the muzzle device is as close to the vice as possible. This position helps stabilize the barrel for later steps.

I’ve found that a rotary tool with a reinforced cutoff wheel such as Dremel’s #426 wheel effectively cuts a line parallel to the muzzle device’s long axis. Before starting, I measure the muzzle device’s outside diameter at the point where I plan to make my cuts. I subtract from that number the average OD of that type of threaded barrel and divide the difference by two. This is my depth of cut to reach the threads. For example, most .223 Remington/5.56 NATO AR muzzles are threaded ½-28 threads per inch.

Measuring several threaded muzzles gives me a range of 0.495 to 0.498-inches. A smaller OD at the threaded muzzle means more metal has to be cut away so I use the lower OD measurement of 0.495 in order to err to the safe side. For example, a recent muzzle device calculation had a muzzle device OD of 0.847 and a threaded muzzle OD of 0.495. Subtracting 0.495 from 0.847 yields 0.352 inches, which is the total cut depth of both sides added together.

Dividing 0.352 in half gives a 0.176-inch depth of cut to reach the threaded muzzle on each side. I subtracted an additional 0.005 for a cut depth of 0.171 on each side to add in a larger margin for error since these cuts are being made with a rotary tool. Obviously this is not precision work. All of the error margins stack up to require more effort in the next step but that’s far preferable to finishing removal only to find a longitudinal cut across the barrel’s threads.

I use a steel six-inch rule to measure depth periodically as I make cuts. I’ve found that cutting approximately half the depth on one side before beginning the cut on the opposite side, and then alternating between the two, works best. Most muzzle devices have a sort of ring in front of the muzzle just forward of the threads that serves as a baffle to aid in braking. This baffle needs to be cut through on both sides to allow the muzzle device to be split.

Since a cutoff wheel will often get too close to the actual muzzle and crown when cutting through this baffle, once I’m close I reposition the muzzle device so that it’s held vertically in a padded vice and switch to a hacksaw. If your rotary

The drilled channel the pin was inserted can be seen on top of the barrel threads in this photo. cuts are directly opposing, the hacksaw blade will glide nicely through both sides of the slot you’re created. Slowly cut until you breach this ring of steel. Once through, I return the barrel to a horizontal position and complete my cuts on either side to the required depth. My goal is to get to that 0.005 buffer I built into my depth calculation.

The rear portion of the muzzle device closest to the step in the barrel’s OD will be diffi cult to cut to full depth because of the cutoff wheel’s semi-circular cut profile. You’ll likely be several thousandths shy of full depth in this area. If a crush washer or other thick spacer was used to time the muzzle device you’ll have a small safety buffer to keep from cutting into the barrel step. Cracking the Nut Once the cuts are at their required depth the goal is so split the muzzle device away in halves.

I use a large fl at-blade screwdriver — the wedge-shaped carpenter’s type, not a hollow ground gunsmith’s bit — with a small hammer and nail puller to crack the muzzle device, literally. This is done by methodically working on each cut with the nail puller and hammer, while incrementally driving the fl at-blade driver into the front of the muzzle device along each cut in turn, working from front to back. I work on one side, then rotate the barrel 180 degrees and work on the other side, repeating as necessary.

This is where adequate barrel support is a must since you’ll be lightly hammering the tool into each cut as you attempt to over-stress the muzzle device. Depending on the type of muzzle device being removed I sometimes find it easier if I peel it back like a banana from the front. This helps stress the muzzle device within the cuts so that they eventually crack. Once I see a crack form at the bottom of either cut, I know I’m on the downhill stretch.

I’ll next attempt to work the opposite side to force a crack there as well. It is not critical to have cracks within both cuts but it will help. Once cracks are evident, I no longer drive any tools towards the muzzle. To prevent damage to the barrel I pry the two halves of the muzzle device apart until they pop off. Most often, one side will fall away and the other will need to be gently tapped off due to the pins continuing to hold it in place.

Be very careful not to allow contact between any tools and the barrel at any time. Being too aggressive on any one step can result in severe damage to the threads or crown. Clean Up If you use caution in the removal process, the only reminder of the pins and welds will be the holes drilled into either side of the threaded muzzle.

After cleaning off several years worth of carbon and thread locking compounds, I chase the threads with a ½-28 die, check the condition of the crown, re-cut if necessary and proceed with the rest of my work. Removing a muzzle device with simple hand tools is not a difficult process as long as you take the time to do it right. Salvaging an otherwise good barrel is well worth the effort and saves your customers undue cost. In the end, everyone is happy.

Steve Adelmann is a retired Special Operations Soldier and 21 year veteran of the US Army. He owns Rifleman Consulting, LLC & Citizen Arms, writing and building custom rifles for freedom loving Americans. Go to rifl emanconsulting.com or citizenarms.com for more information. Sources: BATFE-Firearms Enforcement atf.gov Dremel dremel.com AG