Got that made.
Installed it on the gun with the 1/2" piston valve.
Took the airgun outside.
Laid it down on the porch, and went to get the air hose. (Lest I forget, it's pretty cold here. We still have about a foot of snow lingering from the last snowfall.
Almost back to the airgun, and I hear a crack.

The 3/4 female fitting that is glued to the piston side of the 1/2 tee, cracked open.

It has a metal 3/4 inch adaptor threaded into it.
Because that 3/4 female adaptor is glued to the tee, the piston valve is now trash.
Now I can't test the breech loader until I get the 1" piston valve done, and the gun re-assembled with the 1 inch Pvalve in place of the 1/2 inch Pvalve.

Oh well, I guess I know what I'll be doing late tonight. LOL