VTer,when I made up my 2018's I was tuning for a pair of Mojo Stiks.One is 48" and the other,53#.With a slight change in sideplate thickness,these two bows like the same arrow.
I cut the 2018's to 30" and modified the 2016 brass inserts to fit them.I used 175 gr field points to get good flight on those bows.Those arrows with 3,5" fletch,weigh 652 grains.Now,I know most people break out in a cold sweat when you talk about that heavy an arrow out of bows of that poundage,but I like the weight,have no problems with the trajectory at hunting distances(I don't shoot 3D)and am impressed by the performance.I have since switched to carbons and they are heavier yet.
I also tuned up a set of 29" 2016's for those 2 bows,also using the 100 gr brass inserts and a 145 gr field point seemed to do the job.They weigh 602 grs.
Again,nobody makes the 2018 brass insert but it isn't hard to reduce the 2016 inserts to fit.There are 3 sizes of 100 gr brass adaptors for aluminum arrows-2016,2117 and the largest size escapes me.