Best way to get sniper longshots?

Currently trying to get a gold pellington and have done all the camos except the 25 rapid kills (weapon level not 50 yet) and I need about 20 more longshots as well. I have done all my grinding for this gun on nuketown so longshots are not too common as you can imagine so I was just wondering what the fastest way(s) is to bang out these last 20 kills?

Thank you :)