I have at least one modded foam dart ("Nerf" style) blaster using an aftermarket barrel, and which is firing accurately enough that I do not feel it necessary to use a “SCAR” barrel specifically.

Therefore, I came up with this model so that I can give the blaster an orange tip (or of course, any color tip that you prefer, but I like orange).

From my printer and on (I believe) a reused Nexus Pro barrel, it is a VERY tight fit.  However I do not intend to need to remove it.