[Nightblade]

Thank you for your answers.

After viewing the save game, i tried myself and noticed that i was right : 1 MG unit+1 sniper are able to put the spider nest in "pinned down" situation.
In my previous battle situation 3 Iroquois MG firing without stopping during several turns are not able to have it "pinned down" despite they sometime hit (with no penetration of course).

And that was my problem, as it is impossible to assault a spider nest if it is not pinned down, the "booby trap" weapon from the guy inside of the spider nest is a "squad kill" weapon.

I am not really understanding why so much armor to such unit, but following the saved game i tried to assault the 2nd spider nest using the MG+sniper tactic, but from the entrenched position to its north (for cover).

After pinning down the sniper nest 2 times (it took +/- 3 turns of full fire on the nest to pin it down once), i succeeded to move in contact 2 marine squad 2 times (so 4 assaults in total)
for the precision, the marines were at 1 or 2 suppression level for each assault.

It failed 4 time and at the end , it made the 2 Marine Squad annhilated by the spider nest booby traps (as after each assaults it was back in "ready, dug in" stance).

So i can accept the fact people say those spider nest are not "invulnerable".

But considering the time in turns it takes to just destroy one, how easy it is to fail an assault, and the huge losses in the assaulter ranks due to the booby trap retaliation, they are way better than any kind of bunker i ever met in the 1960/70 battles in the game if you have no artillery or no APC.