Get hold of Mormegil's tank range, and run it as a "Listen Server".
Then get used to how tanks looks at known ranges.
Unless you are firing "short" PzIV or JS-2, most guns have a flat enough trajectory that it's pretty easy once you get the 250m, 500m and 750m ranges straight.
I use the technique that I believe the German crews actually used. I estimate the range, put the top of the pointer on the bottom of the target, and add a couple of hundred meters to put the shell through thre center.
If you can't find a copy of the map out there, PM me, and I'll email you a copy. I've tried his old link, and it's not current anymore