The first order of bidness,is to keep the horse in front of the cart...and to simply scratch things offa da list.
Speed,BC,ES/SD are known quantities(as quantified by the OP) and them are good things to have wrapped tidily. Such essentials,routinely meld in harmonious conjunction with numerous Boolistic Calculators and while there may be subtle deviations amongst the software ranks generated comeups,the differences ain't ever stark. Good info input,will reliably yield good comeups on the output.
The obvious that all are missing and are all too giddy about poking the pony behind the cart,is erector travel. To reliably arrange POA/POI intersection,you gotta deduce the flight characteristics of a given load,in a given atmosphere and have the means to RELIABLY alter it's course of flight,to intersect where the crosshairs are looking. To say the erector travel of the aforementioned 6-18x is suspect,is gross understatement. While easy enough to quantify,with but a single 100yd poke(so as to remove as much atmospheric from the equation as possible)...I'd be re-hitching the pony to the FRONT of the cart,prior to that easily discerned confirmation.
I'd haveta ascertain where the erector falls at the zero range and that in regards to the windage's relationship to it's mechanical center...if only for starters. It is undoubtedly cast hard to port or starboard and that will do no favors. Secondly,I'd wanna know where I was at in ele travel,regarding my zero and how much travel remains beyond that. Nailing both of them prudent points,is default money makers that'll bear copious fruit,lonngggggggg before loading(or firing) the first round for a new rifle. Hint.
Mounting systems is always suspect(both in their relative quality/integrity and their installation/torque),but I'll cast a gracious wand and go out on a limb and assume 'em to be in synch. Keep in mind that short receivers,closely spaced rings and long tubes(especially multi-segmented 1" versions)...are not a recipe for long term zero retaining satisfactions. Re-hint.
Now unto the crux and carts pulling ponies. You did not get a box of "soft" BC's. Nor did you get a transonic slip,in regards to the range(s) thus far cited. You did not get pinholes at 100 and keyholes at wayyyyyyy supersonic,due your twist rate...despite the hilarity of the chatter thus far associated,with such ruses. The odds on given,is that you've an erector which did not travel the full distance you input,regarding it's ele travel as the firing solution.
Soooooooo...cut to the [bleep] chase. Revisit the 100yd line,hang vertically stretched butcher paper and a nice little black dot at it's bottom. Then simply dope the erector travel for the solution that fell short and paste the crosshair on the single bottom dot. After that poke,simply measure the distance from aiming point to the boolit's hole and extrapolate the erector's travel as per that solution. Re-re-hint.
I know it'll take ALL the fun outta guessing and will allow you to cut to the [bleep] chase,but I've personally long had a warm/fuzzy for KNOWING and right outta da gate. Odd how them led to water,follow suit,after having seen the light. Do not be "suplized" that you find an erector soft spot,regarding it's ele travel...in a glass sighted hard to port or starboard. Nor be "suplized" that ele tracking changes,when nearing the end of the ele's cited travel. Further,understand that the full realm of ele travel is IMPOSSIBLE to realize,with an erector cast to port or starboard. Re-re-re-hint.
When you ain't dealing in KNOWN(proven on paper) quantities,regarding ele travel accuracy,ele range of travel and an ele erector's ability to track straight...then you is simply pizzing up many ropes and a guess is as good as you can ever do. Physics is a wonderful tool to bank upon and etched in [bleep] stone,which is why I find it curious that soooooooo many are in such a hurry to question it and long before the weakest link of ANY system and that being the erector proper.
You've been led to water. Re-re-re-re-hint.
Now as to dealing with an erector who's "click" graduation values as a single or in compilation,deviate from a cited design designator...who gives a [bleep]?!!? Simply denote the values and do bidness on the erector's adjustment,in correlation to the known values and POA/POI will reliably intersect. Rest assured,your stock don't give a schit,if the comeup solutions denoted on it's card...ain't harmonious with the graduation values slated by the Manufacturer. If/when encountering a flat spot in the travel(which is very typically at/near it's ceiling),simply denote when/where it falls and do bidness in those accords,if you are too cheap to skew the mounting system and ring the [bleep] bell.
Simply beat on schit and let it prove it's merit and weigh them findings as if they was gold...if only because they are. If/when sumptin' is suspect,focus upon keeping the pony in front of the cart and troubleshoot in that manner.
Pass the modest X's,shorter tube length,greater internal erector travel and hold the fluff.
