Shouldn't all the weapons be blocked by the gate just as the player is blocked by it?

Look at ff_avanti_classic for example. The 30 seconds waiting time before the gates at the start of the attacking team open have the same issue. I always thought this was a problem with gates only on that map.

You also have the thing with maps that have rosters placed on area's to walk over, like balconies (Take 2nd cap point on Anticitizen for example). If you place a turret on top of those rosters and an enemy walk underneath it, the turret will be able to lock on and shoot, through the roster if needed. "Luckily", players like scouts and medics can shoot back with nailguns and shotguns to "clear" the turret.

So I'm getting the idea it's a global property of a gate / roster which allows this to happen, regardless of the sniper being able or not able to do it...

What is a Roster?

oh, meant a grate of course :)

I'm not talking about starting gates--those should of course block everything and it's easily fixed. Any material that uses the surface property "metalgrate" or "chainlink" is supposed to let bullets pass through.

I also do believe that they should go through

So a gate is not a wall.... the most gates are open for real.... but only half of the classes can shoot through..... close it or open it.. my opinion... and in real life most gates can shoot through

There are certain other odd places spread among the maps sniper rifles cant shoot through as well. The open area between pipes on some hand rails, the big vertical bars that make up the sewer grates on dropdown when closed... the fenced vent where the flag is on the same map just a couple of examples.

Snipers can't shoot into water either.

?

IIRC, I've killed plenty of underwater enemies from 2fort's battlements.

Then it's a Well thing because I can never damage anyone underwater on Well and I've shot so many people in that situation.

No problem with that here. Was playing ff_well yesterday and shot Bully a few times with the sniper through the water, near that room with the water and bridge in it.

Might be a graphic setting?

I run all the graphics on max but I would be surprised if the graphics did this.

If I'm outside the water, say at the spawn exit on well and a demoman comes to blow the grate and drops into the water. I am genuinely unable to damage him the moment he goes beneath the surface and I am really not missing this shot often.

I will have to get it on demo when I play FF again.

I've killed tons of players in the water on Well...