Full bore porting, main valve dimensions..

[Machinist]

"so flat bolt-face is for versatility"

Even a slender probe impedes airflow.  Bob's bolt has no probe.  The flat bolt pushes the pellet to the correct depth, then the bolt is pulled back out of the way, away from the projectile, providing an unrestricted path for airflow.   

Steve

[rsterne]

Here is what I mean by an angled exhaust port.... I like this much better than a vertical exhaust port, I feel the flow is much smoother....



All that is needed is to round the corner just to the left of the "P" using a small spherical burr on a Dremel.... I usually use a 1/8" diameter, and work carefully through the exhaust port....

Bob

[Fruit-Dove]

and that diagram clears out everything...

The flat bolt pushes the pellet to the correct depth, then the bolt is pulled back out of the way, away from the projectile, providing an unrestricted path for airflow.   

yes...the J-slot it is..