movement – How can heavy-armor melee characters practically close in on ranged enemies?

Install Jump Jets or a Jetpack

Assuming this is even a problem, say you are so slowed that your movement speed is under half of your opponent, allowing them to kite you in combat, you can always install mods on your armor to increase your mobility, most notably: Jump Jets and Jet Packs.

Jump Jets

Capacity 20; Usage 2/action

You can activate jump jets as part of a move action in order to fly during your movement. You can fly up to 30 feet (average maneuverability) with a maximum height of 10 feet, or you can fly up to 20 feet straight up. You must land at the end of your move action. Jump jets can’t lift you if you’re encumbered.

Jetpack

Capacity 40; Usage 2/round

You gain a fly speed of 30 feet (average maneuverability). You can use this for “cruising flight” at a usage of only 1 charge per minute, but you are flat-footed and off-target while doing so. Changing from normal flight to cruising flight or vice versa is a standard action. A jetpack can’t lift you if you’re encumbered.

Both consume a single armor mod slot, and are available early on, 3rd level item for Jump Jets, 5th level item for Jetpack. They are fairly cheap too, 1000 credits for Jump Jets and 3100 credits for a Jetpack.

A Jump Jet mod was literally the very first thing I bought when the GM said that 3rd level items were available for my vesk mechanic that had a sad 20-ft movement in heavy armor. I did not regret it at all, it helped my mobility in combat, it helped me to get through some obstacles (cliffs, pits, walls) and it looks cool in combat when I declare that I jump over my enemies and land on the other side of the battle.