Air Venturi Avenger 177 ammo and tune?

I picked up an Avenger in .177. Pretty much all the info I can find is on the 22 or 25 version. Anyone got some helpful tips on where to start with this thing? Primary use is plinking at 50 and 100 yards so I’m thinking slugs?
With my 177 I've found a reg pressure of 12 to 1300 and hammer spring 1 to 2 turns in work best. I've tried good pellets like h&n and some from south America named apolo with no luck.the best I've found are Crosman 7.9 h point and the 10.5 domed. I know jsb are what many say work best but I struggle with the price. I just shoot paper. If I was killing things I'd be more serious about getting a heavier pellet.
 
Not sure if yours is the original avenger or the newer avenge x ?

I don't think there is too much of a difference, other than the regulator.. so this will probably be relative.

Here is what I personally found with the avenge x in .177