1496 for 1500 game

Grey knights 1496 point list
HQ
Grand Master 145 points
Icon of the just 25 points
Psycannon 30 points
Total 200 points

Elite
Brother Captain 61 points
Bionics 10 points
Terminators x5 230 points
Psycannon 25 points
Total 326 points

Troop 1
Justicar 50 points
Grey Knight 3x25 75 points
Grey Knight +Psycannon x2 100 points
Total 225

Troop 2
Justicar 50 points
Grey Knight 3x25 75 points
Grey Knight +Psycannon x2 100 points
Total 225


Heavy
Dreadnought 80 points
Assault cannon 30 points
Incinerator 15 points
Total 125

HEAVY
Dreadnought 80 points
Twin linked Psycannon 50 points
Missile launcher 10 points
Total 140 points


HEAVY
Land raider crusader 255 points
Total 255

I'm not too keen on your GM and Grey Knight Terminators.
I think you'll get more from a Incinerator than a Pyscannon. So drop the Pyscannons while inside the LRC.
Also I'm not keen on Icon Of Just it's just too expensive, you can nearly get another Terminator for that!
I think you should add Hammerhand, it'll be great for dealing with Walkers seen as Strength 6 won't do much.

I then think your Grey Knight Terminators should be made the GM's Bodyguard. This way they'll use the 40k Retinue rules.
It'll stop your GM from being sniped in close combat.

I'm not keen on Pyscannon Knights. But I guess it's one the best objective based Troop for GK's...

Your Dreadnoughts are good, but a single Land Raider instead would be better. It'll provide better A.T. and will protect your Grey Knights inside.
Also I think you made a typo on TL pyscannon.
I would then go onto use GK's w/incinerator inside the LR.