This ain't the Gospel Truth, but if you read this before you drop against the clans you'll have a better chance of being on the same page as the rest and beating the clan's favorite (only?) invasion tactic.
I put this originally in the FRR forum but since I keep dropping with PUGs and other IS groups its seems like we need better cooperation, so in that spirit here goes:
Been fighting all weekend against mostly Clans and mostly in Leoben as part of the 1RDR. We were successful in repelling most "zerg rushes".
Anyway, here are my tips that seem to work consistently at blunting the Zerg Rush:
NUMBER 1 (thanks to XenoBlitz for pointing this out during our matches today):
Be prepared to die. Think Kamikaze. Your enemy is already thinking Kamikaze when they rush. The normal "pull back from fire to cover" does not stop the zerg rush. You need to be smart but be prepared to sacrifice and get the next mech quickly. Bonus is that the dropship has good aim and you drop near Omega. Do not be meek or you will lose.
- Always have at least 1 scout near every gate before and near the end of the rush. Obvious but it happens all the time that 1 gate is without a spotter.
- Set up the line of fire along the most likely route (e.g. to the right of beta gate for cold map) and have some heavies blockading their rush route while meds and lights hit them from behind as they move in. Flow back to Omega/Cannon as they push inward.
- Make them eat arti strikes as they come through the gate! Great for reducing armor on the legs.
- Don't worry about killing them. Just leg the mech and then leg the next one, etc. If you have the cannons just shoot legs and let someone else get the kills.
- Forget LRMs. Bring Ballistics! Really. They have too much ecm and missiles have limited stopping power.
- Regarding the above, I like multiple UAC5s for their rapid fire rate and range. I note that legs are the one place most people reduce armor so it doesn't take alot of hits to leg a Stormcrow.
- Pack as much ammo as you can fit in there without sacrificing armor. General rule of thumb is 3 tons of ammo for each UAC5.
Dropship loadout "Dakka in your face" (240 ton limit):
- King Crab 4UAC5s, 3MLs and something like 13 tons of ammo (11 heatsinks, runs hot) 300std engine
- Ilya Maurits 3 UAC5s 3MLs and 10 tons ammo 260xl engine
- Yen Lo Wang 2 UAC5s 2MLs and 5 or 6 tons of ammo 255xl
- Locust Hero "at least I have ECM and arti-strikes"
good for nibbling on their legs or zerg rushing if you have to counter-attack

Dropship loadout "Dakka Force" (A little more mobile mix):
- Ilya Maurits 3 UAC5s 3MLs and 10 tons ammo 260xl
- Yen Lo Wang 2 UAC5s 2MLs and 5 or 6 tons of ammo 255xl
- Shadowhawk 3M 1AC5 (2tons ammo) 1UAC5 (3 tons ammo) 2MPLs 280xl
- Jagermech Hellboy 2UACs (9 tons ammo) 2MPLs 4MLs 255xl (lots of good jager builds but you get the idea)
Obviously we need to be able to shoot moving targets so if you are a bad shot stick with lasers or try LBX10s (good for legging).
Hope this helps you kill more Clanners and take back our FRR planets!
Edited by Jman88, 16 December 2014 - 04:30 PM.