I don't understand why they sent 6kg springs with this set in the first place, when you look on the spring section of the store, they specifically recommend against using the 6 on the AT kits. I was unable to prime the AT with the 6 in, and I'll have the stock spring in until the 5kg arrives. I hope they will offer some explanation to their reasoning.
Most of the time I go after flys, I use a Fly Zapper, which is like a tennis racket, but with an electric mesh, some of them actually POP!
The thing about power, a lot of the time, id takes a few hits to kill one, but I haven't found any since I got my Recon w/ OMW stage 1&2, so I wouldn't know how well it works. I can't wait until spider season though.
Normally we do just move them outside. But some, like the family of two inch long monsters we had recently, we're not willing to get that close to. But most of the small spiders, we just ignore.