Last night I finally made the top 100 (94th to be exact) and had over 150,000 skull kills. Tonight..

World ops lasts for a set time period (a week I think) it then resets to zero.

I have the same question. In that case, in the next cycle i should be getting skull coins and it should again restart my ranking. In the second week i.e. the new PvP cycle, the skull coins do not accumulate. It goes back to zero after every game and I am unable to improve my ranking. In the first week I was able to reach rank 60 and then again I am back to some where around 500,000 or 600,000 without any improvements even though I finish on top at each game. Like I am making 9 to 10 kills in each game.

Your SCORE resets every 6-7 days. You keep your rank but not your ranking. The ranks are copper silver gold (animal). The ranking is the top 3 4-10 11-100 and such like that.

You also keep your battle tokens to upgrade stuff with.

If the comments said here are true, then how do you finish on top of world ops??

because there are free weapons available as gifts when you finish on top of world ops. Moreover people are using weapons to kill me in PVP mode which I cannot find in the game if I search all the snipers available in normal mode (even if they are locked) or even in special weapons category. Please shed some light.

I have also noticed that my hard work is not paying. My rankings in World ops are dropping every now and then as well as the rewards attached to them in the tier rankings.