in a .50, with round balls for projectiles; I like a rifle with a 30-35" tapered barrel (1" down to .75"), weight between 6.25 and 7.5 lbs, with a balance point approx 4-5" in front of the bow of the trigger guard, LOP of between 13.25" and 13.5", with approx. 2-2.2" of drop at the comb (I prefer a parallel comb), I don't worry much about cast (I find I don't need it, others do). I am 5'8", approx. 18.5" across the shoulders (arms down at my sides), arm length (finger tip to shoulder) of 28", index finger tip to elbow of 17.5", approx. 7 inches between top of the shoulder and corner of eye (standing straight).
Growing up, we never went to a "range" and never rested guns, unless we were sighting them in/ load development (seed bag or bag full of old rags on a tailgate) or a post/tree was available. Everything was done off hand, we didn't use tree-stands or blinds; we always spot-and-stalk (my younger brother did buy a tree-stand when he was younger, but it rarely gets used) for everything from 50yd groundhogs, 150-200yd deer, 100yd coyote, or my 165-170yd groundhog (with a .22, I might add, 1 shot, held about 18" over his head (he was standing) from a 110yd zero, got him in the bottom of his ribcage lol) (when I first got into the forums, I was amazed at how short of range people considered "ethical" or "practical"). With the exception of 2 rifles, all of my family's arms are open sighted. Supporting hand goes just in front of the trigger guard, both elbows are tucked into your ribs. holding a gun this way completely changes how different weights and balance points feel, with almost all of the common commercially available traditional ML guns being excessively muzzle heavy (especially the straight barreled ones without lead in the stock).
For a light bullet rifle (sub 350gr .50 bullets), I'll keep it around the weight of a ball-rifle; but with a heavy bullet-rifle (you'll appreciate it with 600-700gr .50 bullets), I go up to 9-10 lbs by increasing the barrel dimensions (keep the same taper), and add a little weight to the butt. If you "had" to have some 40+ inch barrel, you would increase weight to around 7.25-8.5lbs. Same method for everything from .32 up to 10 bore shotguns. In .32, that can get me a 35" barrel rifle down around the 6lbs range for a bullet rifle, or if it's purely a squirrel gun/ (I don't like that long of a barrel with such light loads, you start to get excessive fouling at the muzzle), down around 4.75 lbs (lighter barrel and stock). .58's would range from 7.5lbs for a ball-gun... all the way up to 11-12 lbs for a BPE-type gun (with 175gr charges and 625gr bullets, you want the weight). Balance and fit are most important when it comes to an off-hand gun, with just enough weight to keep the recoil tolerable with your max loads (especially in a hunting/general purpose gun you'll be hauling around all day). As far as dedicated off-hand target guns go... move the balance point forward 2" and make it as heavy as you can hold up for the relay you'll be shooting (you have to set it down at a bench to load between shots anyway).