A barrel assembly for a paintball gun includes a first barrel portion, a second barrel portion, and an insert. The insert is inserted into and positioned within bores of the first barrel portion and the second barrel portion. The first barrel portion and the second barrel portion include corresponding connection mechanisms that allow the first barrel portion and the second barrel portion to removably couple with one another. The insert includes a ridge that is fixed positioned between the first barrel portion and the second barrel portion when the first barrel portion and the second barrel portion are coupled. The first barrel portion and the second barrel portions can receive inserts with different bore sizes (e.g., inner diameter).