Thats crazy the 243 is a great gun with the rite bullets get some 100 gr nosler partitions and dont look back corelock bullets are great as long as your shooting atleast 130 gr but the 100 gr dont always get the job done. If your having trouble killing deer with a 243 its the ammo or bad shot placement, you said she was a good shot so it must be the other.I got one......get rid of the 243 for deer hunting and pick up something bigger like a 270. I know alot of people who have trouble with deer and 243s. Although realisticlly not too many people can just go out and buy a new gun, I have to ask what grain of a bullet are you shooting? I would say that you should get a load with more powder in it but this would cause your scope to be off. I have a 243 that I use only for varmits I want to make sure I do not injure the animal at all, I even shoot 100 grain for coyotes and stuff like that.
Why do you want it to pass through the deer? If a bullet passes through, then its taking some of its energy with it. If it stays in the deer, then the bullets energy stays and you get the hydraulic shock. If you want one to pass through, any full metal jacket bullet will--though they wont leave much of a blood trail (and are illegal to hunt with).