Hey, its me again, i want to change the weapon damage of my dmr, i think its to low, but where can i do that?

Open its projectile tag, look for impact damage effect. Then edit that.

thanks, but i have a second question, my marine misses almost every shot, so i changed the projectil error from 2 to 0 at the ranged combat section, but he sitll misses, do you know why?

couple of other things you can try paddy.

also under ranged combat.
target tracking, how well the ai tracks its target. 0 = not at all. 1 = perfect all shots should land.
target leading, how well the ai predicts the movement of target and the positioning of the crosshair to match. 0 = sort of. 1 = perfect.
damage per second, how much damage a target will receive, regardless of shots hit

Also know that the projectile's velocity as well as it's air/[water] gravity scale can affect how AI use the weapon.

Messing with the target leading and tracking in the .actor_variant should cover the time it takes for a slower projectile to hit the target, as Ally stated above. Check 'AI must use ballistic aiming' in the .projectile tag if it arcs.

On a side note, the 'projectile error' under the .actor_v says it is how much error added to each projectile fired. Not 100% on this, but it may just be that the marines are using an already inaccurate gun to begin with. Try reducing the error in the .weapon tag first to see if it helps.

Check the actor variant's burst geometry. Return width and stuff might be too big. Also, check the guy's weapon damage modifier if they're too weak.