Some shooters want the shortest package possible without giving up real sound reduction, and that is the shooter the Fatboy was built for. The original Fatboy earned a loyal following, and in the 2.0 version we gave this Campbell soup can a facelift with a new outer shell design and interchangeable calibers from .177 up to .30. In this Field Notes post I want to walk through how the Fatboy 2.0 works, where it makes sense on your rifle, and how the muzzle brake, extension tube and ribbed end caps let you build on it over time.
The DonnyFL Fatboy 2.0, 2 inches in diameter and 4.25 inches long.
Quick Summary
- The moderator: Fatboy 2.0, 2 x 4.25 inches, 6.7 oz, .177 to .30 with 3 interchangeable air strippers and a 1/2 x 20 rear cap.
- The brake: the M51 Fatboy 2.0 Muzzle Brake screws onto the front and uses the Fatboy caliber inserts, 2.9 oz.
- More quiet: the 3 inch Fatboy 2.0 Extension Tube captures more air, and it is also compatible with the Ronin and Emperor.
- Easier removal: Ribbed End Caps fit the Fatboy, Ronin and Emperor.
What the Fatboy 2.0 Is Designed to Do
The DonnyFL Fatboy 2.0 measures 4.25 inches long by 2 inches in diameter and weighs only 6.7 ounces. The large diameter is the key to its design, because it gives the expanding air a large volume to settle into inside a very short overall length. The result is a moderator that will surprise you with its performance for its size, while adding very little length to the end of a carbine or bullpup.
Interchangeable air strippers
The Fatboy 2.0 includes 3 interchangeable air strippers, which is how one moderator covers .177 through .30. Matching the air stripper to your caliber keeps the bore line appropriately sized for the projectile you are shooting, and it means the moderator can move with you if you change rifles or calibers down the road.
The redesigned rear cap
The rear cap was redesigned in 1/2 x 20 threads for easier gripping and installation. Most DonnyFL adapters are built around 1/2 x 20, so the Fatboy will mount to a very wide range of airguns using the same adapter you would choose for any of our 1/2 x 20 moderators.
The new outer shell and the redesigned 1/2 x 20 rear cap on the Fatboy 2.0.
The Fatboy Muzzle Brake
The Fatboy 2.0 Muzzle Brake is a muzzle brake or air stripper that screws onto the front of the Fatboy. It is made of 6061 T6 aluminum in black anodize and weighs 2.9 ounces. It does not come with its own individual air strippers, because you change the caliber size using the inserts that were included with your Fatboy.
Adding a brake to the front of the Fatboy gives the air one more stage of disruption before it leaves the moderator, and because it uses the same caliber inserts, it stays consistent with whatever caliber you have set the Fatboy up for.
The M51 screws onto the front of the Fatboy and uses the Fatboy caliber inserts.
The 3 Inch Extension Tube
If you want to make the Fatboy quieter, the Fatboy 2.0 Extension Tube adds 3 inches to capture more air and reduce the muzzle blast further. It is 6061 T6 aluminum in black anodize with a matching outer tube design, so the finished moderator looks like one piece. Expansion chambers do not contain internal baffles, which keeps the extender simple and light.
The extension tube is also compatible with the Ronin and Emperor, which makes it a useful part to have if you run more than one of our 2 inch diameter moderators. The product page for the Fatboy mentions our longer extender as well, so check the listing for the length that suits your build.
The 3 inch extension tube matches the Fatboy outer shell and also fits the Ronin and Emperor.
Shop the Fatboy Extension Tube
Ribbed End Caps
The Ribbed End Caps fit Ronins, Emperors and Fatboys, and the ribs give you a better handle to make removal easier. Please keep in mind that with this cap installed, the suppressor will not fit into the red storage tubes.
Where the Fatboy Fits Best
The Fatboy makes the most sense where overall length matters more than anything else, such as bullpups, carbines and rifles that ride in a truck or a blind. Because the system is modular, you can start with the Fatboy alone, add the M51 brake, and add the extension tube if you find you want more quiet, without replacing the moderator you already own.
If you are choosing between the Fatboy and a longer, slimmer moderator, our Sumo Field Notes and KOI Field Notes are a good comparison for the other end of the spectrum.
Fatboy 2.0 Setup Checklist
Choose the air stripper that matches your caliber.
Mount with your rifle specific 1/2 x 20 adapter.
Add the M51 brake using the same caliber insert.
Add the extension tube if you want more suppression.
Re-zero after any change to the moderator.
Frequently Asked Questions
What calibers does the DonnyFL Fatboy 2.0 work with?
The Fatboy 2.0 is compatible with .177 through .30 caliber, using the 3 interchangeable air strippers that are included.
How big is the Fatboy 2.0?
It measures 4.25 inches long by 2 inches in diameter and weighs 6.7 ounces.
Does the Fatboy muzzle brake include air strippers?
No, you change the caliber size of the M51 using the inserts that came with your Fatboy.
What thread is the Fatboy 2.0 rear cap?
The redesigned rear cap is 1/2 x 20, which works with most DonnyFL rifle adapters.
Does the Fatboy extension tube fit other moderators?
Yes, the 3 inch extension tube is also compatible with the Ronin and Emperor.
Final Thoughts
The Fatboy 2.0 is a short moderator that you can grow into, and that is what makes it such a practical choice. Start with the moderator, match the air stripper to your caliber, and build on it with the brake and extension tube as your rifle and your shooting call for it.
