Snap hits the upright
 

This happened in an actual game.

QB is in shotgun on his own 5 yardline. The snap is high and hits the right upright. B11 recovers the ball in the endzone. What do you have?

Safety when it hits the upright.

This is a safety because the ball is considered out of bounds in the end zone.

Peace

the uprights just like the pylons are out of bounds behind the goal line.

The ball is out of bounds when it strikes anything which is out of bounds including players who are out of bounds, and pylons and goal posts.

Players are out of bounds when they are touching anything other than another player or official out of bounds. So by extension a player who is touching a pylon is out of bounds, and a receiver who runs a route, and accidentally kicks a pylon mid-stride, or brushes against a goal post on the end-line has committed a 15 yard penalty for illegal participation. (Go figure)

So by extension a player who is touching a pylon is out of bounds, and a receiver who runs a route, and accidentally kicks a pylon mid-stride, or brushes against a goal post on the end-line has committed a 15 yard penalty for illegal participation. (Go figure)

If I'm not mistaken, if he stays OOB...there's no foul. It's if/when he returns to the field. There's no penalty for any player running OOB during the play.
Correct..?

correct, if he kicks the pylon and stays out of bounds, no problem, if he never goes out of bounds except for hitting the pylon then he's out and back in almost instantaneously...or when the upright is on the endline like at a lot of smaller schools and the receiver crossing the back of the end zone brushes the post.

As was discussed in another thread ad nauseum...since there is no definition for an inbounds player only an out of bounds player then you cannot be simultaneously in and out because if youre out youre out. So the player standing in the back of the end zone who leans against the post or brushes the post or turns and the back of his foot kicks over a pylon has while standing "in bounds" gone out of bounds, and then when he stops touching said post or pylon, being no longer out of bounds is inbounds and if its an A player then he's "gone" out of bounds and "returned" which is illegal participation 15 yards.

This is also why you should make sure the back pylon that lines up with the hash marks is beyond the end line. It does not need to be on the end line and can only cause problems like this if it's there. We have to move in in 90% of the games we work.

Can anyone explain what those are for, other than as guides for whoever lays down the lines?

They come in really handy on snowy, muddy or poorly marked fields, where you don't have visible hash marks to line things up.