I think we have the equipment(rifles, anyway) to be successful, just haven't figured a good way to point 'em from 100 yards to 400 yards consistently.
I have custom built long range rifles and shoot long range competiton for many years. But when it come to long range hunting, I prefer to use the older methods. My personal rifle/caliber is a Rem M700 LH BDL in 30-06. Box stock except it has been piller bedded, scope rings lapped, trigger worked on, etc etc. The scope is my 25 year old Leupold VarII 4-12 w/ AO and a std Leupold duplex reticle. Needless to say it doesn't have target turrets either.
When describing my setup to fellow hunters using their newest super magnum with a huge POS scope and mutiple turrets sticking out of it, they say, "ok, see that rock over there... hit it!" I lay down, pop out my bipod legs, range the distance, and figure out my holding point and bam.... smash. I have had 2 hunters tell me no way you can you can be sighted in at 100yd and still hit something at say 300-400yds on demand. Not bragging but with some knowledge of your equipment and practice it is relatively easy with your existing equipment.
BUT..... I DO have points of aim out to 400yds (and more, just haven't run the numbers and tested it out yet) using this scope without touching the turrets once I have it sighted in. The key is having the std Leupold duplex in the scope. Not the heavy duplex because it covers up to much of your target at longer ranges. I have used this system for years, but it takes a little getting use to.
What I do is put the scope on 4 power and sight it in to be dead on at 100yds where the top heavy duplex reticle meets the thin crosshairs. Where the thick and thin meet actually is an arrowhead and I sight in on the tip of the arrow head. I call this point (Point A) What I call my "Point B" is the actual true intersect of the thin crosshairs. And "Point C" is where the thin goes to thick on the bottom creating an arrowhead pointing upward. I hope this description is clear.
This gives you 3 aiming points to use without ever touching your turrents. This method works for the yardages you are talking about. And depending on the caliber you are talking about possible aiming points out to 500 to 550yds without holding over a deer sized animal.
Now back to some more details. FYI: These details are for my 4-12 power scope. You scope power and reticle size will probably be different. But it is not a show stopper. Just take a target with heavy 1" grid lines on it and tack it up at a true 100yd distance. Put your scope on low power and find out how many inches there are between your Pt. A, Pt. B, and Pt. C. They will be different but the same logic applies.
Here is my exact details:
Sight in dead on at 100ys at Pt A (you can go an inch or so high depending on your hunting situation) Where I hunt I can shoot 400yds but I need to be prepared for the short precise shot also. So I elected to go dead on at 100yds)
for 200yds with a dead on hold using Pt A, I hit about 2.5-3" low on paper. so in the field I either jsut don't worry about those 3" or simply jsut hold the height of the heart on on the chest.
for 300yds I crank my scope up to 12X and use Pt A and hold dead on. I shot a 2 shot group about 3 weeks ago double checking my zero and it printed about 1" low at 300yds. That 1" at 300 is negligable in my book.
400yds is still at 12X but I then use Pt B (actual crosshairs).
Being I can only shot out to 400yds where i hunt i haven't tested past there, but obviously I have another aiming point at Pt C to give me even more yardage, but like I said. I just haven't tested it or tried it. Doing the calculations you should have aiming points out to 500yds with the average med bore caliber and typical bullet weight and drop chart.
Hope this helps. I gotta run for now. If you have any questions let me know. The biggest thing is training yourself to use the Pt A aiming pts by instinct and not automatically use the crosshairs when a big buck pops up at 50yds in the thicket. So don't switch to this method without a lot of preseason practice or it can be frustrating.
The nice thing is that you don't have to spend any money on a custom reticle or turrets. Use what you have and you can shoot out to 500yds with practice and a little measuring to know how many MOA your reticle represents at what yardage.