Nerf Rival Knockout Short Dart Barrel Mod

For years people have been modding the Nerf Rival Knockout for its power, size, and simplicity; it's a great blaster. Modifying it to shoot short darts has historically been a pain, though. Whether you were using brass, aluminum, or polycarbonate, each mod took copious amounts of time, and the results were inconsistent. This 3D printed barrel aims to eliminate much of the work while producing replicable results. Short darts for all!

Parts:

There is only one model of the barrel, just many file types for your convenience. Aside from that, a pair of pliers (for stuck metal rods), some snips, a screwdriver, and some silicone grease (optional) will come in handy. The short dart holder adapters can be found here, and an extended version is also available here.

Printing:

Due to the small surface area of the barrel nose, you will want to watch the print. Most of the time it has no troubles, but you can add a raft or brim if you want to be on the safe side.

Assembly:

Here's a quick video that shows how to install the mod and what the final results look like. You may want to trim the air restrictor more for increased airflow and dart velocity.

I don't have a chronograph but was able to take some slow-motion footage at 480 frames per second, giving me a pretty accurate estimate (plus it seems to be about pacing the Aeon Pro).

Notes:

You will want to apply silicone grease to the inside lip of the larger barrel opening (where you load it) to improve the seal. You could get away without it, but I don't recommend that. Also, the inside of the barrel is intentionally tight. As short darts are used, they wear down and the foam gets compressed, making a looser fit. The barrel is this specific size so that the darts don't fall out when the blaster is in motion. 

If the barrel is just too tight for you (maybe differences in print quality), you can edit the STEP or F3D file to loosen it a bit. Only widen the barrel by 0.05-0.1 mm. The other option is to take some sandpaper to it - your choice.