OK, I'm making a new weapon that replaces the conc rifle. It has it's own template. OK, the problem is that in MP I can see the shots and it seems that people get hit by them, but everyone else can only hear the sound, and that's all.
So I replaced the shot it fires from the custom template to +concblast or whatever. When I fired then everyone could see the shot and got hit. Here's the template:

+pla**** _explosion thingflags=0x1 light=0.100000 timer=0.400000 sprite=pla****.spr soundclass=exp_plas.snd typeflags=0x53 damage=2.000000 damageclass=0x8 blasttime=0.300000 force=10.000000 maxlight=0.500000 range=0.100000
+plasbolt _weapon thingflags=0x20000401 light=0.400000 vel=(0.000000/8.000000/0.000000) explode=+pla**** fleshhit=+pla**** damage=15.000000 typeflags=0xd cog=JKW_pball.cog
+plasmi**** _explosion thingflags=0x1 light=0.200000 timer=0.500000 sprite=mi****.spr soundclass=exp_raildet.snd typeflags=0x17 damage=250.000000 blasttime=0.700000 force=750.000000 maxlight=0.800000 range=0.375000 debris=shrapnel_1 debris=shrapnel_2 debris=shrapnel_3 debris=shrapnel_4
+plasmissile2 +grenade1 thingflags=0x20000400 timer=2.500000 model3d=pMsl.3do size=0.003000 movesize=0.003000 puppet=ra.pup soundclass=mssl.snd creatething=+lgflash cog=00_smoketrail.cog airdrag=0.000000 height=0.003000 physflags=0x200 vel=(0.000000/5.000000/0.000000) angvel=(0.000000/0.000000/90.000000) explode=+plasmi**** fleshhit=+plasmi**** damage=50.000000 mindamage=25.000000 typeflags=0x240b81
+plasmissile +plasmissile2 timer=10.000000 typeflags=0x24020d

whats up with the stars? Anyway, try Hideki's custom projectiles in Multiplayer at http://millennium.massassi.net