if you could put any attachment on weapons?

Shotgunception...

Since everyone is jumping on the "explosive bolt" bandwagon, here's one:
Any shotgun with explosive bolts. Do I need to say more?

While explosive bolts are a fun thing to have on your weapons it also has a heavy drop and becomes increasingly useless at range. So if you really want to be mincing infantry: The pump-action Solid slugs on <any fast-firing weapon>, add a BRRT or whatever it's called for fun.
Just imagine it: GD7F firing solid slugs at max ROF? That's gotta hurt. And even if it won't be as powerful against MAX's as the explosive bolts, it has better velocity and ranged power against anything else. Same thing for LMG's, AR's, SMG's... I think the best weapons would be the accurate low-damage one's so your shots are more efficient and the "low damage" is now compensated by powerful slugs.

On a more "normal" level, any shotgun would be good with a suppressor. It's not as if the increase in recoil is going to make it even worse than it already is.

all sniper rifles with iron sights or 1x reflex (for real, not a joke)

i'd actually love that too, 1x scope is my go-to scope, even for longer ranges
out of all 1x scopes i'd have to say VS have the best too

Kobalt mag size on P-120AP.
Lol 52 round gun.

Actually interesting... Any gun could do with a Kobalt magazine size increase.
Wouldn't some other weapons be better then? If I remember correctly the Vanguard doesn't have an RPM, which can be seen by the fact that the reload starts instantaneously while the Prowler has a 0,5 second between the last shot and reload starting (again, if I remember correctly). This would mean the Vanguard could fire his entire magazine instantaneously. That's some nasty alpha-damage right there. "Instantaneous" in PS2 equals "as fast as the Server can process the commands", we can see how fast that can be when you get almost insta-killed from collision damage so with careful trigger discipline you wouldn't fire your entire magazine away instantly. Even with "just" a magazine-size increase of 3 you can obliterate any tank from behind (4 shots instantaneously), with 6 you can obliterate any tank period. It would even be foolish to go higher levels since you would simply shoot your entire magazine away too fast, better take that reload more often.

Flashlight on needler.

Chaingun with underbarrel EMP launcher and extended mags. I would also like when equipped an actual grenade belt.

Crossbow that shoots your faction specific activated power knife as ammo.

Phaseshift with the TV guide of the Phoenix, replacing its scope with a mini-game essentially.

Blackhand with iron sights.

Anti infantry grenade launcher turret, placed on ground pointed skyward, an AI turret with the cool down of AV turret with singular missile replaced with a grenades with high damage and wide AOE. It's supposed to be ridiculously OP.

Not sure what the term is for it the turret grenade launcher idea.

Despite all the wacky idea's, I think the rules were to stick with the current attachments you have along with the limitations on them. So if you put a barrel attachment on you can't put another one on.

NERF!

Lumine Edge with underbarrel shotgun.

Blackhand with HVA and silencer and extended mag.

Carver with advanced laser sight.

Ehehehe.

Lasher with:
2x optic, flash suppressor, extended mags, explosive rounds.

You know you're getting hit by AoE BUT WHERE?!

Mattocks with:
No optic, advanced laser sight, flash suppressor, slugs

Sniper max!

Minichaingun with:
1x reflex BECAUSE I ******* CAN!!!, flash suppressor, advanced laser sight, recon darts.

INFILTRATORS WORST NIGHTMARE!!!

Godsaw with:
1x reflex. Godsaw is perfect as is.

Battlegoose with:
2x, flash suppressor, advanced forward grip, HVA, for unlimited sniping.

I probably have some other ideas but eh.

I remember once some-one saying that that the game can't handle more than 1000rpm guns, although I have no idea if it's genuine or not. If that was true, that's still even enough shells per second to kill any tank in the game from any side in a second.

A tank-buster with a kobalt mag-size would also be lol, or any vehicle gun that has more than 1 ammo in it's mag really. 58 mag-size furys, 60 mag dusters.

High-Velocity Ammo on MAX Bursters.
And 6x scopes for the Vortex!
And a bipod for my knife!

12x scope on any shotgun

Ac-x11 with a silenced underbarrel piston shotgun with smart choke and laser sight equipped

12x scope and forward grip on Chainblade. Oh, with soft point ammo.

The option to unlock and attach six suppressors to the minichaingun.

SILENCER ON A TANK!!!

Ok joking,silencer on the Blackhand maybe,uh,i dont know...

UB Shotgun on Magscatter. You know you want it.

BRRT on the RAMS. How does this work, I don't know, but it will. It will! DAKKA!

Jackhammer with Explosive Darts. You just swipe across the screen during one burst, and the screen breaks down into a mess of explosions.

Blackhand with Silencer, so we can see just how far we can push the length of a pistol into unreality.

Seriously, I just want some form of Forward Grip on my Butcher. The horizontal recoil on that weapon is atrocious.

Just lemme shove smart choke on the baron and have a shotgun with spread so tight that it's essentially a sniper and then i'll be happy