AAhh. Sorry.
if you're up for a video tutorial, check out BFX on youtube. This webshow shows you how to make cheap props out of household items, and, although I'm pretty sure they haven't done a sniper rifle tutorial, they had done pistol, shotgun, and rocket launcher tutorials, so you can probably pick up some tips from them.
Another option would be an airsoft sniper rifle (similar to a bb gun, but modeled after real guns). these can be kinda pricy, though, but you might be able to find one that doesn't work for cheap.
best of luck