My best advice for this weapon is:
lead the target , concentrate at hitting the point where your target WILL BE, not where he is cos actually the hagar roundds are fairly slow, i find.
Then, (and this is the hard bit) the further away you are , the more distance you must lead your target by.
The problem with this is.. htf do you know where your target will be?
Prediction!
I find this works well if your target is by an obvious objective. ie armour or health, i don't try and hit the player but spam the crap out of the pick up cos if the target player goes to pick it up you'll probably get at least three hits.
Also, ammo is key with hagar, at lest 100 rounds before it's even worth arming.
If you get like 300,

, other players be like:
'well he'll run out in a bit i'll just keep running'
