I'm not very good with 3d design software, so I decided to start off with something simple like this. I think it turned out very well and it improves the blaster by a lot. The barrel is now very stable and I can now shoot more accurately. Not only that, but I don't have to constantly adjust the barrel. I just have it friction fitted on right now and it works perfectly.
I printed it at 300 micron resolution with 10% infill. Because of the low resolution, I had to sand the inside a little bit. After minimal sanding I got it to fit. For my first 3d designed part, I am very happy with how it turned out.