Having 16020 kills for 45 tails means an average of 356 mobs killed per 1 drop, so even assuming you always doubled the drop with swell body (and it’s safe to assume you didn’t double every single one, right?) it still means 1 tail every 712 monsters killed, I see nothing wrong there, the OLD dpk number was somewhere around 450-650 monsters killed for one, so assuming it isn’t changed (even tho I think it is) you’re just slightly above the average, nothing wrong there related to the dpk system per se imho.
Also, take into consideration while reading above that I assumed you successfully swelled every single drop, and with the current system being so unpredictable it’s a very hard thing to do compared to the old one, so if we tweak the numbers a bit and presume you doubled only half of them the average goes even lower than the previous old dpk value.
I’m currently farming the same monsters for my second orange weapon (I finished my Astra Bow months ago) and i’ve noticed that even if sometimes I get one at 800+ monsters killed, sometimes I get one as low as 100 monsters killed, it still averages 450 in my book, so: yeah, farming orange materials is a huge pain in the ass, but it’s nothing out of this world if you consider that before the balance patch, most of these weapons were better than Solmiki’s and they don’t require you a 5man setup running every day for X weeks/months (and even post patch, they still remain insanely good).
To all the guys here complaining (not talking to you obviously) I can only say you should get to it IF you really want it, or stop complaining, you really are not cut for things such as these and you shouldn’t even pretend to be.
If you don’t like games were heavy grinding is involved, clearly ToS has never been the game for you! Sorry if this may sound rude (it surely does) but this games has always been like this, farm/grind heavy, and even tho I myself still complain sometimes about it, you need to accept that’s the nature of this game and if it’s not to your liking or if it’s not fit to your gaming schedule, then you need to accept this and move one, you can’t ask to change the game entirely to fit your tastes.