I'm not overly familiar with the HvZ rules, but I do LARP with nerf guns and boffer weapons, so I would like to offer the following advice. If it's allowed to put the Raider drum in another gun, do so. Reloading during a fight without having someone to cover you will get you killed, and six shots doesn't always cut it. While the Raider's slam-fire is great, the ranges are pretty bad and the accuracy is garbage. There are a lot of Longshot mods online that you can use, but there are two problems. First, you have to find a Longshot. Second, the Longshot is awful if you haven't modded the internals. It jams up, chews darts, and wastes air pressure. And if you mod it, be careful and reinforce it. The best mods for distance and accuracy will break the internals. Then there's the issue of cutting/filing brass tubing. If you have the time and money, then by all means, get your hands on a Longshot. If not, get a Stampede. Get at least two Raider drums. I know that some Toys R Us stores sell a Raider that comes with two drums. Get a pack of extra darts while you're there. You WILL lose some. Get the bandolier (or make one with a luggage strap) to steady your aim. Get a shotgun shell bag from Wal-Mart to store your extra drum, ammo, and a sidearm (preferably a Barricade).
This also needs to be said: get two boffer weapons, or the sword/board combo. Your weapon will fuck up at an inopportune time. Jams can't be cleared and batteries can't be replaced in combat.
If there is any night-time combat going on, get dark grey clothing. It blends in much better with the shadows than black. Make use of all the cover you can. Move quickly and quietly. Learn to serpentine. And if you smoke, realize that there's a time and a place. Hell, switch to snus for the weekend if you can.
Finally and most importantly: when you win, /tg/ had damn well better see a picture of you holding this thing in a Commissar outfit.