// Location.
	unreliable if ( Role==ROLE_Authority && !bCarriedItem && (bNetInitial || bSimulatedPawn || RemoteRole<ROLE_SimulatedProxy) )
		Location;
	unreliable if ( Role==ROLE_Authority && !bCarriedItem && (DrawType==DT_Mesh || DrawType==DT_Brush) && (bNetInitial || bSimulatedPawn || RemoteRole<ROLE_SimulatedProxy) )
		Rotation;
 

So you wont get Location and Rotation updates for if RemoteRole==ROLE_SimulatedProxy.

I went through this and tried a lot of different things to make it work. In the Food Fight mod I made a Frying Pan weapon that I originally wanted to be able to deflect incoming projectiles back at the sender or off into some random direction. I had varying degrees of success but ended up settling on destroying the projectile then spawning some smoking wrecked chunks to simulate the pan destroying the projectile. It works pretty good visually and has the added benefit of working with any subclassed projectile and there's no online weirdness that you may or may not account for ahead of time.

227 only?

If not, your only real choice is to destroy and recreate the projectiles.

If you call .Destroy() on the projectile server side then it will destroy on the client too.

This is a sick read but if you print it and then take your time you can work though most of it:
http://wiki.beyondunreal.com/Legacy:Replication_De-Obfuscation

Here's a chunk of the code from the FoodFight frying pan. This check occurs when the weapon fires (it swings out in front of the player). If it finds one it spawns some smoking chunks, a small flash, and also destroys the projectile.

      //looking for an incoming projectile
      foreach RadiusActors(class'Actor', F, 300, Owner.Location)
      {
    	  dir=F.Location-Owner.Location;

         if((normal(dir) DOT normal(X)) > viewangle)
         {
       	  HitLocation = F.Location - normal(dir) * F.CollisionRadius;
            if (F.IsA('Projectile'))
            {
               if(F.IsA('Chunk') ||F.IsA('ForceFieldProj') || F.IsA('Arc') || F.IsA('Fragment') || F.IsA('ShellCase') || F.IsA('FFProjectileDeco') || F.IsA('Mtracer'))
						return;
					//found a valid projectile, spawn some effects and destroy it
          	  for (i=0; i<(3); i++)
	 			  {
						b = Spawn(class'ProjectileFragments',,, HitLocation);
		  				b.Velocity = vector(RotRand()) * (FRand() * 200);
					}
					Spawn(class'SpriteBallExplosion',,,HitLocation);
					F.Destroy();
	       		PlaySound(sound'Gong1', SLOT_None, 150);
            }
    	  }
      } 

Remember to mentally sort between what is simulated and what isn't. Calling destroy on a projectile will replicate that out and destroy it on all clients provided you haven't made changes to it's replication roles. Destroying something that's simulated will remove it for that player only (with exceptions for sure, it's not that simple lol).

Don't give up yet, you are really close to the key turning in the lock.

We are playing DM together and you fire a rocket at me. The server sends out the rocket being spawned as well as it's direction to both of us. The server is in charge of this rocket and accepts input from us that may affect what it does but it has the final say.

On screen your game creates the rocket. The server tells your game "Spawn it here and point it that way". Your local machine renders all this but your copy is local. In order to really affect the rocket you need to tell the server you want to do something (like jump in front of it). If you pulled your internet plug at this second you could blow up the rocket but the server's rocket would still carry on flying.

This is why your mod works locally but not on server. In order to rebound a rocket You need to tell the server to totally change the direction of the projectile. You can do this in a minor way (see function TraceAltFire() in the impact hammer) but to do wholesale reflection you really need to destroy the projectile then create a new one oriented in the direction you want it to go. You can do that easily on your local system since it's all simulated and there's no need to share this new information with anyone else.

I hope that helps.

(Edit: I should add that you need to do the creation of a new one because direction [velocity] isn't replicated often enough. Projectiles don't need direction replicated often since they continue on their path until they are acted upon. Consider the ripper blade...it flies straight until it hits a wall, but then the code kicks in and changes the direction for it. Since both client and server have that code the client can accurately predict the path and render the blade with periodic updates from the server and it all looks smooth. Take that code-assisted prediction away and you end up with the alt-guided redeemer that looks all herky-jerky as you watch someone fly it. And that's with a ton of added code to help it be smoother.)

Send me your mod. Let me look at things, I'll bet you it's something simple you are overlooking. I can't tell you the number of times I've done that and someone else looks at it and sees the issue in moments. You most certainly can get too close to your code.

The bottom line is that if you properly destroy a projectile in code and that code is not simulated then it should destroy it on the server (oversimplified but mostly accurate). If it doesn't then you need to declare some missing replication for your inventory item so that command passes from client to server. The code bit I posted is from 'state NormalFire', and state code is set up all the way back in 'object'.

If you are calling the visiblecolliding in your OP from a new function you are declaring then you need to set up replication for that function most likely, or you could move that into a state code that is already replicated.