Another useful technique is to spam Catalyser charges. As many as possible and explode them at once. Tones of damages.

People would perhaps be more helpful if OP gave some information other than 'gun' and 'plz".

If you know how to shoot and how to shield-cancel and switch*, there's really not much else to teach. It's all about practice and using your brain (yes you actually have to use your brain if you want to be good at Lockdown). If you repeatedly miss people when gunning, figure out how you can correct your aim to improve your hit rate. In different circumstances, different strategies may be better. There's no "best method" for all situations.

*You should know how to do this from using swords.

So, you want to learn how to gun in LD, huh? While Lord-Cerrin and Auto-Target have posted some nice tips on gunning, they both require brain cells and skill to pull off.

Instead, I am going to tell you about the proper way to gun. The only way to gun. The PRO way to gun
It is in fact SO PRO that the people from THOSE guilds use it on a regular basis, even if they are playing against 1 year old monkeys and people with arthritic hands. But who care about them anyways. It's all about getting them quintuple digits :D

So, without further ado, here it is! The PRO way to gun!

First of all, you are going to have to turn on AT (or at least have the Toggle AT option bound to a key you have easy access to). No no no. Don't worry about the death threats you will receive because of this. Those words you see in front of the screen are just that. Words. :3

Secondly, ignore the capping points. You won't need those. It's all about getting them 5 anyways.

Finally, target players who look totally lost. Once you are close to them, stand still and let AT give you a tiny (0.000001%) boost to your awesome skills. Remember to run away like a little bi... I mean, retreat if someone manages to nearly take you out. If done correctly, as long as you keep your distance, your opponents will fall, even if they attempt to get too close to you. Also, a pro tip. Don't forget the names of the ones who managed to nearly beat the holy snot out of you. You'll want to avoid them unless they are busy trying to fight off others. In that case, it is okay to get close and shoot them with down with your newly acquired PRO skills. ;)

Now, here are some things to keep in mind.
- Remember to /yawn, /sad, /cry, /laugh or yell LAAAG whenever your opponents happen to take you out by some miracle. Chances are, if you happen to be in one of THOSE guilds, you will look godly.
- If you are using striker, spin around as if you had ants in your pants. No no, you will not look ridiculous. You will once again look like an LD god, especially if you have one THOSE labels under your name.
- You MUST have a Black Kat Cowl. Sell your kidneys, your toes, your mother, your mother's mother, your mother's mother's mother, your younger siblings. Heck, blow off your entirely life's savings if you have to as long as you can get a Black Kat Cowl. Also, have a sword with you, preferably a Flourish or Acheron. Now hold on hold on, hear me out. The sword will NOT be your main weapon. You don't want to get to close to someone that can potentially eliminate you. Instead, use these swords when you get a lucky... I mean, intended shock or freeze on them and beat them down for trying to beat a god like you.

Follow this method and you will be an LD gunning god in no time. Heck, you might even get your own personal smoochers like the ones the PROS seem to have ;)