9/16 or 17/32 barrel? Pseudo Sleeper breech

This might be a case where an illustration will help make your explanation clearer. While I believe that I might be correctly understanding the construction of your breech, I could also be completely wrong in my assumptions.

A quick reminder that telescoping brass tubes are sold with listed sizes that refer to their outer dimensions, their inner dimensions are equal to the next listed size down.

Anyway. From what I can tell you have a 1/2" ID polycarbonate bolt that leads to a 17/32" brass stub acting as a throat that then connects to another 1/2" ID polycarbonate tube that acts as your barrel. So, depending on the tolerance of your polycarbonate tubes, you actually have a consistent 1/2" ID along the entirety of your design.

Personally, I would err on the side of reliability and open up the bolt to an ID that is slightly oversized so that dart chambering doesn't experience any undue friction. From there you can just run a tighter throat or some sort of taper in the initial stages of your barrel to get a more optimal dart fit. Although it's probably worthwhile to note that historically Angel-style brass breeches were made with fairly loose barrels.

/r/Nerf Thread Parent