UPDATE: I built my breech today, its really straight forward, a hole in the barrel the size of a golfball and a piece of sch80 that slides over it. The hole has some tape inside to act as a detent so the ball doesnt roll out of the barrel. After putting the breech on I sorta feel like adding a sch80 muzzle break to get the white and grey fittings of different sizes on the gun. Tell me what you think.
Specs:
Its a 1 1/2" porting in a 2" tee, sdr21 for the barrel, and 2" sch80 for the chamber, I used sch80 because I got a great deal buying it by the length so I have tons left over, and because its rated to 400 psi. Pilot is a 3/4" sprinkler piloted by a blow gun. After my tennis ball gun leaked a little where I attached the quick connect I decided to sacrifice some pilot volume (sorry jsr

Breech loading should come tomorrow I just have to sand down the inside of my sch80 cause the fit is slightly too tight.
Only a few damage pics for now because I only made it today so I only went to 40 psi until Im confident the cement has completely cured. I promise Ill up the pressure and the damage.
Any feedback/ recommendations welcome, the tape one the barrel and pilot supports will be replaced with hose claps hopefully tomorrow.