What's the diameter of the NERF Longshot CS-6's barrel extension?

I'm currently using the existing Longshot barrel extension for my Recon, and I want a replacement for that to put one on my Longshot to make it look like a... well, a Longshot. If possible, could anyone recommend me a diameter that would fit snugly and yet still be able to be removed? I don't want it falling out while firing or holding, or not being removable.

Ferrari5767 years ago
 I'd say about 1/2"