Best for removing thick paintwork.

[normal rules]

I think I am going down the rollering route. What's best to sand a heavy paint finish before getting the roller out?

[boatbuilder]

Orbital sander with 400 grit to start then go to 600 before paint

[New Kentish Campers]

Orbital sander with 400 grit to start then go to 600 before paint

Agreed, though if the paint is very thick and still soft underneath- quite possible too, then you might find that the heat from sanding would quickly clog a fine grit like 400. Personally, I think I'd go p120 to shift the main think layer, then 180, before applying any primer. Try not to bust through the factory electro-coat primer,assuming it's still present during sanding ( probably an olive green colour) then work up to 600 before the final top coat. Preparation is everything

[kevtherev]

Paint stripper.
Ask Lloydy about stripper, he's had experience of it

[Titus A Duxass]

Scotchbrite pads for the angle grinder.
They remove any thickness of paint regardless of the type.

Not cheap but very effective and quick.

We call them CDS Scheibe, I use the lilac ones and get them from Amazon.

[Sir Brixalot]

Has anyone tried synstrip?