1850 Vanilla Space Marines Shoot you in the FACE

[Camael]

HQ:
Master of the Forge
Conversion Beamer: 120

Troops:
4 Tactical Squads
Multi Melta, Meltagun, Close Combat Sarge, Rhino with Extra Armor and Dozer Blade: 900

Heavy:
Devastator Squad (10)
4 Plasma Cannons: 270
2 Devastator Squads (10)
4 Missile Launchers: 460

Fortification:
Aegis Defense Line
Quadgun: 100

Thats 1850 on the dot. The general idea is to set up the devastators and MoF behind the D-line and in a reinforced ruin. I figure that with the new vehicle rules, I should be able to do decent damage to AV 14 vehicles with the MLs. The Devastators and MoF cover the tactical squads as they grab objectives and such, and the quadgun dakkas fliers.
I would really appreciate help with this. Thanks in advance!

[Seirin]

Ok, the idea itself is fairly sound, however...

You're basically trying to play IG or Tau with the resilience of power armour.

Pros: Strong distance fire power, good mid-range fire. Fairly mobile where it counts and you actually have a list built upon a basic tactica.

Cons: You're fragile, nothing tougher than a rhino or a marine behind 4+ cover. Absolutely no CC threat beyond killing guard or tau.

Overall, you shoot well but essentially you're playing glorified tau; if you can't shoot em' all, you die.

My honest suggestion would be to swap from 'vanilla' marines to space wolves. You lose the master of the forge but your 'tactical squads' get much harder, devastators get cheaper and can split-fire, and you get rune priests for psychic defense (will be needed often at 1850, and living lightning is a shed load more reliable than conversion beamers).

[Camael]

What if I were to drop the Plasma cannon Devs for 2 Ironclads with chainfists and hurricane bolters? Would that give me the CC oomph and durability I need?

[Seirin]

Ironclads are ok, but really aren't enough on their own. The weakness is pretty inherent in the entire army, its lack of dedicated CC and resilient units.

Things that would help a bit also..

Power fists on tactical sgts. Makes combat with a tactical squad a little more daunting as S8/AP2 is enough to instant death most MEQ army characters or weaker.

Lose the master of the forge. Hes a gimmick, that's it. Swap him and the plasma devs for a unit of hammer/shield terminators and a terminator librarian or maybe lysander (he gives bolster defenses like a techmarine, and hes tough as old nails).