A Winchester model 94 in 30-30 would be a wretched rifle for where I hunt deer. Most popular deer gun ever. I love this forum lol!
Now this somewhat the point I was making. A 30-30 with a 170 gr bullet, a 44-40 with a 200 gr bullet and the 243 with a 100 gr bullet all have about the same energy, at the muzzle. The 243 bullets have a smaller parachute, retains energy a bit better past the 100 yard mark. The 44-40 is not loaded to the velocities it used to be, and it has a big parachute. When I injured my back, I bought a light 243 for deer season. It did the job, but I'll have to agree with Elmer, "Not much of a caliber". My back improved, and I went up in caliber. 6 mm and 243 performance very much depends on the right bullet, placed in the right spot. It is suitable for the hunter that is not very recoil tolerant. 243's can be had in some pretty light packages, easy to carry and are light recoiling. It has limitations.
If you can tolerate it (the recoil), the 300 Win Mag is one heck of a good deer rifle, perhaps a bit on the big side, but you can buy "Deer" ammo for it. It will also work on Moose and Elk. Going lighter, I think the 6.5 Creedmoor should be ideal for whitetail. Up a bit and you have the 270 WSM, long range energy, also good. In the bush, my favorite is the 35 Rem. It is not a long range gun. From a blind in the bush, at bow range, try the 30-30 with 125 gr bullets, low recoil and flat murders whitetail. During shotgun, a 12 ga slug hits like a cannon, somewhat range limited. I hit a running deer in the neck with a slug, the head stayed on, but was kinda loose. A follow up shot was not required. Hit one standing, through the chest, spun it around. A 243 will not do that. It (the 243) will harvest deer, and sometimes, it lets you practice your tracking skills.
I like the write-up Nathan from Ballistic studies has posted on his site.
https://www.ballisticstudies.com/Knowledgebase/.243+Winchester.html
And, LOL, I love this forum as well. Disagreeing on the 243 as being or not being the perfect deer rifle.
I will concede one point, the bullets have improved a bit since I hunted with a 243, and that should help.