Customizing a Remington V3 Shotgun

Remington has an excellent reputation for the 870, 1100 and 11-87 shotguns. While the “newer” Veramax and V3 shotguns, with a double gas piston system similar to the one found on the Benelli M4, haven’t been around as long, I’ve found them to be an excellent option. In this post, we will take a look at how to customize a V3.

During the COVID-19 pandemic, the availability of long guns dramatically decreased. The most popular shotguns, the short barrel Remington 870 and Mossberg 590, almost immediately disappeared from the market due to demand. This allowed for new exposure for the other guns on the market, like the V3. In this case, the gun was configured for hunting and the owner wanted to add a magazine extension tube and cut and crown the barrel so he could use it for matches and defensive use.

Before we get working, please take a few minutes to read the following disclaimer:

The contents of are produced for informational purposes only and should be performed by competent gunsmiths only. and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.

Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.

For this project, I ordered the following items from Brownells:

The magazine threads on this V3 are the same as a Remington 870, 1100 or 11-87. This means the gun will accept a magazine extension provided it fits inside the front stock. In this case, we will be adding a plus 2 extension.

Next, we have to determine where to cut the barrel. Since this gun has a vent rib barrel, the cut can’t end where the rib isn’t supported, it must end where the rib is supported by a base. While we wanted to end up with a finished length around 18″, the barrel doesn’t allow for that. In the image above, you’ll see the one rib base ends around 17″ and the next around 21.5″. Since I’m working in the USA, cutting the barrel below 18″ can’t be done without a stamp for the end user. We’ll cut this one at the 21.5″ mark.

I like to use blue painter’s tape on the waste end of the barrel to mark the approximate cut location- you can’t cut it any longer if you make a mistake! To cut barrels, I prefer my old Powermatic 143 metal cutting bandsaw. I simply free hand the cut as close to square as possible.

I square the muzzle at the belt grinder. Brownells does sell tools that will allow you to cut a perpendicular crown by hand, but I’ve been doing so many barrels during the pandemic, that this has become my preferred method. It is important to apply light pressure and not allow the barrel to heat up too much during the process. To ensure the muzzle is square, I check it with a small combination square. Once it is perfect, I use some fine abrasive cloth to remove any burrs.

When I cut the barrel off, I also removed the front site. I like to use a 6-48 thread on shotguns, since you’ll often find a wide variety of bead and sight options. I hold the barrel in the milling machine vise, located the center of the vent rib with an edge finder, then drill a #31 hole.

Next, I run a 6-48 taper tap into hole and cut the threads.

The factory front fiber optic sight used both a 6-48 threaded hole, (top right) and a small blind hole for a locating post (bottom left). This post prevents the front sight from twisting. I only cut a 6-48 threaded hole since I wanted to give the owner an option to change to a standard bead in the future and not have the second hole. This means, I’ll need to remove the small locating post from the fiber optic front site I plan on reusing.

I took a small rotary tool with a stone and ground the tiny locating post off.

The factory fiber optic sight is now reinstalled on the newly cut and crowned barrel.

Like many other Remington shotguns, this v3 has magazine dimples that prevent the installation of an extended magazine tube.

The dimples are there for a purpose, they retain this magazine plug (note the grooves in the sides of the plug). Once this magazine plug is rotated into place, the small plastic fingers at the front of the plug engage the inside of the magazine cap, preventing it from unscrewing and keeping the gun together.

I’ve found the easiest way to remove the magazine dimples is to cut them out with a 1/4″ end mill. I gently secure the magazine tube in the milling machine vise then make a plunge cut to remove the material. While you typically use a 4-flute end mill for steel, I’ve found for plunge cutting into thin steel, a 2-flute works better than a 4-flute center cutting in a manual machine.

The new follower slips into place.

Finally I secure the magazine clamp included with the magazine kit. This is a critical piece, since I removed the plug that retained the magazine cap, this is now the part that prevents the magazine tube from unscrewing itself.

Success! We’ve cut and crowned the barrel and added an extended magazine tube to this V3!