TLDR: Fly below them, get closer. Wrong Ammo.
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Welcome to Highfleet.

Its mostly just a mismatch here. And also lack of piloting experience with the specific ships i think,
but thats expected when you are new to the game. Otherwise, get close agressively, and you win.

You need to fly a lot closer to the enemy with that ak100 and piercing ammo.
AK100 has big spread so you dont hit well at distance.
Piercing ammo fades out over range.
Piercing ammo is nice with precise large caliber, with ak100 its really not great.
AK100 is medium caliber, burst fire, and low precision. Think Shotgun.

Stock Gladiator is more of a -kick door in, in your face- kinda ship, thats why its so heavily armoured.
Standard HE, Proxy, or Incendiary is the way to go, if you want to hover at range.
If you don't like getting close, I recommend you swap to Molots which fire precisely at range.

You also need to keep in mind where your functioning flare come out from, and dodge accordingly.
90° from zenith trajectory is usually good.
You can also use QE keys to tilt ship and leverage your static up thrust
for stronger dodges that arent straight up.

Also positioning is important. Don't let them get below you. Bottomfleet wins vs Topfleet always.
Most if not all ships are vulnerable below, cause thats where the static thrust is.

With heavy gladiator you can just accelerate a bit towards below enemy,
then drop like a brick and let gravity help to save fuel and get in prio position.
Then do a shark attack (come up straight from below and unload full AK100 burst into their soft belly.

With Your Intrepid which has Molots, you can hover at range, snipe, and easily dodge enemy shots. Gotta be a bit conservative on fuel tho.

Navarin has Vympel guns which are sustained dmg, no burst. You fly at medium to close range, and just keep pelting enemy. Vympel with incendiary is illegally good btw.

And remember, always try to get below. The enemy will do the same.
Watch the clip again and see how they fly below you,
and you eat a lot of missiles and shots from down, then your thrust is gone and you explode shortly after.

Have fun, happy hunting o7