This is a big-ol Supressor I call "The Compensator". It should friction-fit onto the orange tip. It's designed to be around the same size as the front of the gun, to make it look almost like an extended barrel. This design is very easy to print with no supports (use Cura's "Make Overhang Printable" feature)

Longer

Longer LK5 Pro

No

No

0.2 mm with Cura's Adaptive layer setting (Adaptive layers not nessecary)

5-10%

PLA

If you aren't using Cura's "Make Overhang Printable" feature, you need to add some support. If you are using the feature, set the angle from 30-45 degrees, it changes the model to make unsupported horizontal sections angled, to allow to be printed without supports. Printed with a brim, not a raft. I HATE rafts. Use whatever you want. Keep the model in the original orientation for best printing. Has been tested and need a little bit of shaving where it attaches, since its slightly too tight as is. Just a bit of scraping with a knife or some sanding should do the trick! Sounds very cool too