I've just added a maverick spring to the standard spring in the tube. The blaster is running 12v's and now fires approx. 15m.
After being hit on the forehead by a stefan at 10m from a stampede with the Black Tactical upgrade kit (this left a large swollen egg)
I've used this added spring to give the blaster better playing ability indoors and save the accidental damage, like dents in the walls.
While saying this though I've also bought a BT up grade kit for the $57 K mart stampede we'll get this week.
I've put a BT upgrade kit in the new stampede, it was awesome. I've started to test the limit of what the stampede will take and now I am running a BT spring and a cut down NF spring. It runs nicely at 12v but won't even start at the standard 9v. It may break, we'll see.
I'll do a proper distance test when I have the circumstance (Brisbane's currently underwater). It seems to be up with our modded longshot at roughly 25m.