where is the mercenary camp located that has the gauss rifle unique weapon, the only directions i have are that it is in the far northwest but i cant seem to find it.

have you found the farm where the nightkin is trying to sell you tumble weed

Its a little bit of a walk behind Horowitz Farm (spelling) towards the mountains a bit (north of the map). I recommend going in with a sniper rifle. Kill the guy in the combat armor first, he is the one with the unique gauss rifle. that gun hurts if he hits you with it. Theres probably 5 or 6 mercenaries there, so picking some off with a scoped weapon will help. Theres also 3 Gunslinger Vipers in the Horowitz Farm building too.