Replaces the original Breech design with one designed for 9/16 * 0.028 Brass. The stock pusher and O-Ring create a great seal on brass. Just slide the brass back until it's for enough for the pusher to make a seal (see photos).
Additionally, uses a small ring designed to squish a 113 O-ring between the body of the blaster and the muzzle when you snap the muzzle in during assembly, which retains the barrel.
Both pieces are intentionally a little tight around 9/16 brass. Print settings vary, but bring a nail file just in case. The tight fit also helps with barrel retention, so it won't move unless you want it to, however it's now possible to change the barrel without needing to re-open the blaster..
The author marked this model as their own original creation.