I don't shoot as much black powder as I used to, but I'll put in a word for .45 conicals here.
My father hunted with a .45 TC Hawkin for many years using both rounds and conicals. He took many, many deer with this gun. I shot the same rifle a lot, and when I was younger I used a .45 TC Cherokee (the gun I killed my first deer with). As with any gun, bullet, or shot, placement is paramount. I know that with good placement these two guns were great on deer, most at around 50 yards.
A quick story about my father's .45 Hawkin. We were hunting here in AL in January about 16 years ago. He was shooting about 70 to 80 grains (not sure exactly what is was) and a Maxi-Ball. It was the rut and he saw a very nice buck moving very quickly, chasing a doe. We were hunting a public management area. He knew he only had a few seconds to get a shot off, in a thickly wooded area, full of hunters, with iron sights, on a buck trotting chasing a doe. He decided he should attempt it, picked an opening (I think it was around 40-50 yards), shot quickly,...and knew he missed as soon as he shot......
I've got to mention here, that this is the only shot I ever remember my Dad missing, this is after hunting with him for about 20 years now (only about 4-5 years at that time). It's also a shot he normally wouldn't take, but he did............
At any rate, he reloads, shakes his head in disgust, and keeps watching. About 10 minutes later he sees the same buck walking broadside to him at about 80 yards. He picks an opening (this was a long shooting lane about 15 feet wide that had been cleared), gets a solid rest, smiles, and gets ready to shoot. Right before the buck steps into the shooting lane, it turns and begins walking directly away from my father's treestand. He doesn't even hesitate on the Texas heart shot. Dad sees the buck running off through the clearing smoke. He gets down, finds where the deer was when he shot, and finds no blood. He is able to follow the trail in the leaves where the deer ran, he follows it about 50 yards and is getting worried....still no blood. He knows the rifle will shoot, and felt he had a solid rest, but knew that the base of the tail isn't the same target as a broadside deer. .....
A few more yards and he finds a beautiful 10 point buck. The deer's face is almost grey. It was aged at 10 years old. It only weighted 150 dressed, but it was January and he was rutting hard. The conical hit at the base of the tail, and ended up as a lump under the skin at the base of the neck/chest area. Field dressing was ugly but the buck and the smile on my Dad's face were beutiful. It's the only deer my Dad has mounted although he's taken many that most people would mount. I think he had it mounted because of the hunt and the buck's age more than the rack.
Sorry I got so long winded, but the point is .45 conicals are excellent for deer with proper shot placement. The .50 or .54 may be a better choice if you favor shoulder rather than heart/lung shots. The .50 and .54 also carry a little extra that will help some if you aren't able to get the exact shot you want. This is just a testiment to the accuracy and killing power of the .45 conical with good placement.
Man....it is a long time until October. At least turkey season is right around the corner.
Take care,
JCM