I have some problems with some of your statements, like the one below.
One thing I have noticed is I loose shots it could be going good and the a bullet will disappear.
One thing the 243 demands is a bullet that will perform like the 85gr TSX.
A cheap lightly constructed bullet is not the way to go if you insist on shooting deer in the body with poorly constructed handloads which do not fully close the breech, as you are suggesting.
Personally I have used 6mm Barnes bullets along time ago but gave up on them, because of the fouling they did. But they sure did a good job.
The TSX bullets don't seem to foul, at least not more than any other bullet.
With the 100gr Hornady Inter lock I have never failed to put a deer down in any caliber I tried them, including the 6mm's.
This week's total with the 25 Hunter and the 100gr Hornady Interlock came to 14 deer, 3 Antelopes and 2 coyotes with a total of 22 cartridges. Three complete misses and 19 one shot kills. That is over a period of four years. So I can vouch for these bullets in a small caliber.
If you shoot a deer and it runs away you want to wait for a 1/2 hour before you track them. This will give the deer a chance to lay down and stiffen up and/or die.
Many deer are lost because people keep tracking them too soon. A deer wounded in the late evening will still be there in the moring if left to lay and not disturbed.
Myself I have no use for a 243 as a deer rifle, and never would recommend one for that purpose. They 243 simple produces too many failures in hands of inexperienced hunters.
If you can make consistent head and neck shots at what ever range you are comfortable with, the 243 will do the job well, providing the rifle is accurate.
Why do you think a 338Win mag is not a doe deer rifle? Since you have one why not use it? A better one you most likely wont find. With a 165gr Barnes-x bullet it will take any deer out to 350 yards and it wont stop on its way, in which ever direction it goes through a deer.
Perhaps more gun then you need for deer but it sure has the 243 beat all to dickens.
But if you can't hit a deer at 75 to 150yards broadside, then you better get some practice. No rifle no matter how powerful, will make up for poor shooting. But a bigger bullet will allow for minor aiming errors and still bag the deer.
The reason nobody answered your post, is because you wrote a lot but said very little. You need to be more specific.