Weapons will fire projectiles or hitscan depending on the ammo they are firing. You can go to the ItemList select the ammo item your weapon uses and then go to the Ammo Details. By default all guns included in SGK V2 use projectiles.
If the Projectile is set to a projectile class like the image above then the weapon will fire a projectile when it fires this ammo, you can also set the Projectiles Speed here. If you have created a custom projectile class this is also where you can set that to be used when this ammo is fired.
If the Projectile is set to none like in the image below, then the weapon will fire hitscan (Also known as ray cast) instead when this ammo is fired.
You can find other settings like the weapons range and spread values in the holdable blueprint of the weapon you want to edit, like for example the BP_M4A4.