Never really tried, Velocitus shouldn’t have any issues, Corvas will probably work too - at least it is a pretty good weapon for profit taker, I’m unsure about the Corvas Prime. Against profit taker, it can’t damage a leg if it hits part of the body first, you might run into the same issue against an eidolon.

As for necramechs, the arquembex damage is just broken and doing way too much damage, I thought they said they were going to fix it but never got around to it. Voidrig would be only usable necromech (unless you just want your archgun to have battery instead of a magazine, then either is fine).

You want to try building combo multiplier when you’re using a sniper (use quick shots with a Lanka to build combo and charged shots for breaking limbs), keep shooting an eidolon while it is invulnerable, and don’t forget to armor strip it. They don’t lose weakness to Radiation anymore after being fully stripped. Other than that, hitscan snipers have a slight advantage, they’re able to damage the synovia during the animation where the eidolon is climbing out of the water.

If you’re finding your lures are taking damage and you don’t have/don’t want to use a warframe with healing abilities, you can use the Amesha’s 2. If the center takes damage, it converts that to health for anything within the bubble. Just make sure it isn’t getting in the way of your weapons as its core will block your shots. It’s 1 is also really useful for preventing you from taking damage from the lightning bolts during the Hydrolyst.