My lesser vault gets raider attacks with 4 raiders, while my elite vault gets only 3 raiders. What am I not seeing?

"One extra raider" is not the answer I'm looking for

I think it's random. I only have one vault and I've seen 3, 4, and very rarely 5 raiders hit my vault. It could be that the 3 raider groups are the strongest per raider and the 5 are the weakest per raider so the 4 raider groups would be the middle range.

No idea - I always get four in my 160 dweller vault.

maybe it depends on the amount of dwellers, maybe some specifik rooms ( like radioroom increases deathclaw attacks). cant tell u for sure

Raider weapons and number is linked to the average level of your dwellers. At least in my Vaults.

Hm, that may explain it, Rhynn, since about half of my population is level 1 and in training.

Second this.