@mike243, do please completely ignore any comments about marginal and 150yds, whatever the context.
Others have already said what to do, very sound advice, and that is to practice at various ranges to confirm your drops with your chosen ammunition, and then prove your accuracy with the correct holds. If your change ammunition, you should confirm your drops again. Print out a range card in 10m increments, and go test it at random ranges, deer never stand in nice and neat increments of 100m! Follow this advice, and its amazing how quickly you can learn drops, I get my wife to test me when we drive, she'll pick random ranges off the card and I must remember the hold. Good way to memorise, helps build confidence. I use the card and/or the ballistics app in the field anyway, if you've got time on your side then use it to your maximum advantage.
I drop test every batch of 100 reloads at 300m, two lots of 5 shots. This fine tunes the ballistics app with the trajectory validation tool. I expect a comfy sub-MOA group at that range on a windless day, or with a very light following wind or headwind, shooting prone.
My .243 has roughly the same MV as Mike's with a 100gr SP. With a 100m zero the Weaver BDC reticle's first tick below the crosshair represents ~200m, second tick ~300m. This is at the max magnification, which is what this scope's SFP reticle (most SFP scopes) is calibrated at. These numbers aren't exact but as near as makes no difference.
With regards to range, I'm not so bothered by energy numbers, more interested in accuracy and ensuring the fragmenting bullet damages the right part of the animal for instant incapacitation or a very fast bleed-out. I know the bullet (Sierra ProHunter) opens up and partially fragments at below 2000fps, and will break bone and traverse the width of the chest cavity, so I am 100% confident that if I put it in the right place, it will kill the animal quickly.
I'm really looking forward to testing the new 90gr ELD-X in the .243 Win, as I expect windage performance to improve quite significantly from what the models say.
Max effective range is somewhat elastic, in that wind will determine confidence in the shot. Shots will be taken in no wind or a light headwind at well over 300m with fast killing outcomes, the proviso being that the point of aim is always well forward in the chest. There's enough written about this critical matter of shot placement not to have to write it all again. Anything 150m or less will likely be shot in the neck assuming the animal is correctly positioned and still.
Shoot the deer with a 6mm bullet behind the shoulder, above the heart in the upper rear lungs, and it will run, probably very far, especially if it penetrates between the ribs.
Crosswinds are tricky and max range is reduced accordingly. If I am after deer, I'll actually work hard to avoid having to shoot across the wind. Remember its very different here as our terrain is mental and winds misbehave big time across gullies, especially up around the head of the gully.
Body weights are very important. If I set out to hunt heavy red stags in the 200kg range, I'll take my .308 for the most part. If I come across one with my .243, and its not a monster but more of a younger animal in the 130-150kg weight range, I'll happily take it if I can guarantee correct point of impact. But 90% of the deer I shoot with my .243 are smaller meat deer, so red hind yearlings and spikers usually, animals in the 80-100kg range. Our reds are quite a lot bigger than UK reds, especially Scottish ones.
So to conclude Mike, the max effective range of the .243 Win & 100gr SP is whatever you are comfortable shooting in the conditions on the day, to a max of around 300m in perfect conditions and assuming that you are well practised at that range and know your drops inside out. And...
where to shoot the animal to maximise a fast kill. Which is not a heart shot, because its too easy to be an inch above or behind or even below the heart, with consequent problems. That's what I'm happy with recommending, they fall over readily at 300m with a forward shoulder shot. I've shot lots of deer in the mid-300s with .243 but that's always shooting prone in very high confidence conditions.
On the subject of energy, my view is that whilst more energy is definitely a nice to have,
sufficient energy to ensure adequate penetration and correct bullet performance is what is required. I have never been one for demanding my bullets exit the animal and continue their journey into the adjoining county... I far prefer all the action to happen inside the animal and if there is an exit then fine, as long as the bullet has made a big mess on the way through. Correctly positioned lower front lung shots will generate copious blood gushing out of the animals snout, and you won't have any trouble tracking them because they'll be lying very close to where they were shot!
zeroed at 100 yds factory rounds (SAKO) will give you around 4" drop @225yds and its travelling some.........
deer. capt david
95gr sst small 12 inch gongs happy days as for short range 220 yrd drinks cans end on no problems at all ,practice practice shooting at 1400 feet above sea level it still performed as expected , 
