Excuse the forget out of you? I don't think you know what the forget you're talking about you stupid russkie bitch because the Mordian Iron Guard are not your standard Imperial speedbump, no siree. Not only did these motherforgeters get attacked on their very homeworld by "someone actually formidable" (read: an entire loving Chaotic incursion), but they kicked the unholy stuff out of them. Alone. No support from other regiments, or space marines, it was just the Iron Guard and their lasguns holding off Plague Marines and Great Unclean Ones. They stared Chaos in the face and spat on them, fighting tooth and nail for every single inch of ground until their psykers could break the spell and send the daemons screaming back to Hell.
They also have carapace armor stitched into their uniforms, which means those sharp-looking dress blues provide enough protection to make modern 21st century infantry armor look like a heap of dog stuff by comparison.