A long time ago all weapons were fixed so their length is the same as the length of the model in question, so there is no "ghost reach" due to that. Curved models are specific because the hitboxes aren't curved (so they may hit while it may not seem like they hit, yet).
There is and always will be ghost reach due to lag, especially when movement is involved, because neither player A nor player B see what the server sees. This is of course more common when players are moving quickly. If you don't think it has an impact I suggest you go play on NA (if you are EU) or EU (if you are NA) and you'll get tons of absurd "ghost reach" deaths.
