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What is a “Neilson Device” or “Booster” needed for?

silencer booster assembly
A parade of silencer boosters showing the various revisions over the years.

The Neilson device has several names in the silencer industry. They go by Neilson device, for the person who invented it, they are also known as “Boosters”, Linear Decouplers, or LIDs (Linear Inertia Device), but the most common name by far is booster. Now we need to clarify something here too. These devices do not add recoil back to the system as the name implies. It is actually quite the opposite and I hope to explain that here.

Cutaway booster assembly
Cut-away view of a booster assembly showing how the internal parts are located.

The point of the booster is to allow the host firearm to work properly with the additional mass of the silencer to be on the end of the barrel. The pistol is not engineered with the mass in place so we have to figure out how to get it to work with the existing engineering. The early days solved this problem with silencers that were super lightweight. and then the gun was modified with extra lightweight springs to allow for cyclic operation even with the reduced recoil of the host weapon with the silencer attached. You see almost all pistol caliber handguns made in the modern era are made from what is known at the “Browning” design where the barrel moves back and down to unlock from the slide so the gun can self load the next round in the magazine.

pistol silencer booster
Here is the barrel is “locked” with the slide on the pistol creating a locked breech.

The problem with silencers is that they reduce the amount of recoil the pistol sees and most of the time will reduce it to the point that the pistol will not function properly on its own. The solution is two pronged, one is to not use a silencer, the other is to decouple the silencer somehow to allow the pistol to function properly. Option one is not great as the point is to have the silencer… So how do we solve this? Add a recoil “booster” to the equation.

pistol booster silencer barrel unlocked
Once the barrel moves back under recoil about 1/8″ with the slide, the barrel is moved down like this, unlocking the system.

What the silencer booster actually does is really quite simple when you see it. It momentarily decouples the mass of the suppressor from the gun to allow the gun to operate as it should during he firing cycle. Imagine the magician doing the trick with the table cloth on the dinner table covered in dishes and he pulls it off the table while leaving the dishes behind. This is the same principle that the booster operates at. The gun fires, the barrel/slide combo start to move back as they should and this pulls on the booster piston which compresses the spring. Once the barrel has moved back enough to unlock, the booster will start to reset via the booster spring and this prepares the silencer for the next shot.

It is clearly visible under high speed cameras where you see the silencer booster piston leaping to the rear with the barrel and the silencer module sitting almost perfectly still for a moment (during the pistol cycle). The reason we moved to this design of coupling over the earlier idea is that this requires no modifications to the host weapon other than adding a threaded barrel if it doesn’t already have on. It is simpler and it can be applied to almost any firearm. To use a booster, it is really simple too, just get the booster with the thread pitch that fits your host weapon, screw the silencer module on the side that fits the booster threads and screw the barrel onto the side where the pistol barrel threads fit the pistol silencer booster module. It is also recommended to oil your booster somewhat as you use it at the range, we oil our booster about every 50 rounds or so with a few drops of gun oil on the spring. Basically just remove the retainer cap and squirt in a few drops of oil on the spring so the parts are not dry and screw the cap back into place hand tight. It couldn’t be simpler.

The caveat of adding the booster is that it adds several high precision parts to the system and these are also wear parts that have to be replaced from time to time. This is because of the carbon and soot from the firing of cartridges wears the mating surfaces down over time making the part fitment loose. So don’t think on a booster as a once and done purchase but rather something that wears over time between the host weapon and the silencer that is easily replaced when worn out. We have done several things to our pistol silencer booster design over the years to make it last as long as possible for the end user though and we feel this makes our booster the best choice in the industry because of these features. Some of the things our current boosters use are a stainless steel nitrided housing to resist linear wear. A stainless steel piston that resists corrosion from the moisture in the booster from firing. Chemical resistant o-ring in the retaining cap to reduce damage from the gasses produced from the gunpowder. and so fourth.

If you have any questions about your host firearm and whether you need a booster or not with it, just give us a call and we will be happy to assist you in getting the answers you need. We can be found at 706-661-6911 or at support@libertycans.net

So until next time, keep your powder dry!

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