Reader Tyler Capobres writes:
Before I get into the details of how to integrally suppress a shotgun, please check your state and local laws before attempting this project. Most states don’t allow this, so working on this project could potentially be considered a felony. My state has passed the Firearms Freedom Act, which allows me to build my own suppressors. So long as they stay in my possession, stay in my state, are never sold or traded, and are clearly stamped “Made in Idaho”, they’re fully legal via states’ rights under the Commerce Clause.
The project started because of my initial attraction to the show “Sons of Guns” and their unique builds. In one particular episode, the crew built an integrally suppress AK47. A suppressor reduces the speed of the gas escaping the barrel, which prevents the “crack” you hear when a gun is fired and you’re not wearing hearing protection. Integrally suppressing a gun is different from traditional suppressors, which thread onto the end of the barrel. An integrated suppressor is built into, or attached to, the barrel itself, which allows the rifle to maintain its accuracy, and prevents the rifle from becoming incredibly long and cumbersome.
While integrally suppressing a rifle can be complicated and dangerous without the right tools, I theorized that the same thing could be done with a shotgun, without complex machinery. Shotgun barrels have long been ported to aid shooters in reducing muzzle climb. As the gas escapes through the ported holes, pressure is put on the barrel opposite the direction of the escaping gas. This has a secondary effect of reducing the overall amount of gas exiting the end of the barrel.
Since most shotguns have a smooth bore, you can easily port the barrel without having to worry about damaging any rifling. You still need to make sure that any burs are removed from the barrel, because even the slightest blockage or hindrance to the slug or shot could cause a catastrophic failure.
For this project, I decided to drill five port holes in the top of the barrel, spaced out an inch apart from each other. I started 1.5 inches from the end of the barrel, and used diamond-tipped bits to drill the holes. It’s easiest if you start by drilling pilot holes with a smaller bit, before moving up to a larger size.
To avoid the risk of too much of the wad snagging, I chose to go with 1/8” diameter port holes. Make sure you remove the burs from both the outside and inside of the barrel before continuing. I then tested the idea using a thin, stainless steel cylinder.
(It’s important to note that initial test shots were done with the shotgun in a mount, rigged with a cord for remote firing. I was 30 feet away, behind a three-foot-thick berm.)
The last piece to this puzzle is the suppressor itself. You can use a system of baffles, but I chose to go with an empty steel cylinder for mine, to save on overall weight. You’ll want a steel cylinder that is at least 1/16-inch in thickness. The overall dimensions are personal preference, but I recommend making it long enough so the cylinder extends three inches past the first and last port holes. The larger the diameter of the suppressor, the more gas you can slow down before it exits the barrel.
If you go with a baffle system, you can reduce the overall diameter. For my suppressor, I chose a four-inch diameter tube, with a 10-inch length. I had a local machine shop weld a plate onto each end, and cut out a hole 1/16-inch larger than the outer diameter of the barrel, so it had enough wiggle room to be taken off without too much of a struggle.
To keep the incoming gases from escaping out the sides of the suppressor, I added a rubber grommet on each end. While firing the gun repeatedly, I noticed the suppressor had a tendency to creep forward and fall off, so I added a universal shotgun clamp with Picatinny rail to keep it from moving forward.
What started out as a shotgun that would normally be uncomfortable to shoot without hearing protection, became a new way to enjoy my old shotgun. Even using standard birdshot and buckshot, the suppressor reduced the sound level to the point it was no longer painful without hearing protection.
It isn’t as whisper quiet as suppressors are portrayed in movies, but it’s still a considerable accomplishment in terms of rethinking old ways of doing things. While this was a fun project, I’m sure it won’t be long before someone comes along and improves on my idea, and I look forward to the day that happens.
©2016 by Tyler Capobres,