Unless the other fellow is visibly warping around, your connection quality should not matter at all. All you have to do is hit the picture on your FE. The hit detection is done on your FE. Shoot the picture of him and it hurts him, it's that simple. A higher degree of lag will mean that you are seeing what he did with a longer delay, but that's all. As long as the target is moving smoothly and you can hit him, you will get results. Hit packets go out as TCP I believe, so they will be re-transmitted if required. A bad connection will mean it may take longer for that damage to register and for you to see the results, but it will be transmitted.
If you are seeing hit sparkles and not seeing any results, there may be another problem. When you see this be sure to film it if you can. Then do some traceroutes and we'll try to troubleshoot the problem. Doing things like disabling V-snych has caused problems like that in the past.
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Lephturn - Chief Trainer
A member of The Flying Pigs
http://www.flyingpigs.com "A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"