New player, questions about weapon choice for IF

[Misterduch]

Hi, a new player here. I will be playing as salamanders ( same as 40k ) but I am planning on running an allied detachment of IF.

I was thinking taking a Castellan, 1 tactical squad and 1 heavy weapon squad. Maybe an unit of Phalanx wardens for some flavour.

Question is, what  weapons? I'd like the castellan to have the same loadout as the heavy support squad, this also fits with the IF's specialization in auto weapons. But quite frankly I am at a loss which to pick. I am tempted to go for Autocannons but I feel I would be missing out on the auto cannons. Heavy bolters seem a bit basic so idk.

Any IF players having an recommendation?

( salamanders army is going to be focused on closing in and using flamers, melta and some tanks/dreadnoughts to push the enemy while the IF would sit back on objectives )

 

[tinpact]

Autocannons would be my choice - you get the IF bonus and a good amount of medium-high strength shots at good range.

The Salamanders already have anti-armor covered pretty well, so autocannons can cover for low AV and infantry targets you don't want to use your meltas on.