I'm looking to purchase a muzzleloader and was hoping to get a run down on the pros and cons of round-balls and saboted (sp?) bullets for deer hunting. My criteria (roughly in order of importance) are accuracy, "terminal ballistics" and trajectory/max. range- any insight on these issues would be appreciated. The rifle will either be .45 or .50 caliber, although I haven't decided which yet.

I would like to figure this out now, before I begin looking for a rifle, so that I end up with the right barrel twist rate.

These are just my thoughts on the matter, but here goes. If the majority of your hunting is close (under 125 yds) the patched round ball could be used very effectively. In that case, I would be looking at 54 cal or larger for best end results, with a slow twist (1-60 or so). The diameter becomes an important of the equation. For longer ranges, a sabot load can deliver better end results if loaded accordingly. The twist should become more like 1-30, and the caliber can be smaller, I would not go to 45 myself, but that is just me. I would stick to 50 or bigger for deer size animals. For just pure fun value, patched round balls are hard to beat, IMO. For the longer range shooter, sabot and other conicals may show an advantage. Most of that is up to the shooter, if you know what I mean. I wish the rate of twist requirements allowed both in the same gun, but most guns show a preference for one or the other when they have a compromise twist rate, depending on powder load, bullet fit, patch thickness, lube used. These are variables that can be played around with to obtain a load that operates in the sweet spot of the rifle, for patched round balls, to some extent conicals also.
Go for the fun, shoot a lot, and welcome to the "BP rules" side of the fence. They are like chips, you can't have just one!!!

Good advice 8mm. I agree with every word. I started shooting BP only 5 years ago, but didn't start hunting with one until 2 years ago. Always seemed to fill the freezer during archery and firearm seasons.
For starters I got a really cheap($125)CVA to see if I would even like it before spending more money. That is my advice to you, Belaw. After that, shoot ball/patches over loose powder to stay inexpensive and to see if you even like shooting BP and want to upgrade to a better rifle.
For the sake of expenses we shoot ball/patch for practice, then we switch to sabot/240gr. Hornady XTP's for hunting.
Yes, I fell in love with it. I now have 3 Encore 209x50's with a Bullberry custom barrel on the way within the month to give me a 4th. Yes, I have 5 Encore frames. I have a wife and 3 kids who now LOVE shooting BP since it shoots more accurately and doesn't kick as hard as the shotgun/slugs we're required to use here in Indiana.
Whatever you choose, go for it. You won't regret it. This is a wonderful way to hunt. I only use an Encore BP rifle and an Encore pistol for deer hunting now. Catch the fever!!!

8mm is right about all that, but I've always preferred conicals to anything else. Seems like everybody just HAS to shoot sabots these days and that's what the manufacturers are playing to in the marketplace. I've found RB's to shoot just fine in guns twisted for lead conicals in the past, but it may not always be so. Most people incorrectly equate velocity with range in this country(US), but a correctly designed conical lead bullet will run circles around sabots if you really feel the need for range. I'd rather see a fellow Hunting with RB's than one Shooting with sabots. JMO

My question to you is why do you want to muzzleload hunt? To relive the past? To lengthen the season or have an opportunity to kill more game? Just to get in the field with buddies? Seems to me that these are the biggest influences on what you want. Nowadays, when you pick the gun, you're picking the projectile as the guns are rifled with a twist appropriate for a narrow range of projectiles.

The 1-48 twist of the TC sidelocks will shoot both round an conical well. The faster twists are specifically intended for sabot. The slower twists are specifically intended for roundball. Roundball is effective. I would not be living today if it wasn't (it fed my ancestors pretty well). It is in the application that it differs. If you want .30-30 level performance, you don't want RB and you probably aren't interested in reliving the past (or you just aren't realistic).

I sometimes hunt with my smoothbore flintlock (during regular gun season when it is legal in VA) so I guess you know where my interests are.

I like the traditional muzzleloaders, so here goes what I think. A .50 cal ball is very efective on deer out to 100 yards and the .54 even more so. I have a Lyman Deerstalker with a 24", 1 in 48" twist barrel, that is the best hunting rifle I own for in close work. I hunted with a friend that had a Lyman Greatplains rifle in .54 with a 1 in 60" twist that was very accurate out to 125 yards or so, but I found it too long and heavy for hunting in the bush. We used balls in these rifles. If you want to go to a .45, I think you should go to a faster twist and shoot bore sized bullets. The Whiteworth rifle is in .45 that uses a 500 or 550g bullet, and is noted for long range target shooting. Whatever you get, go with a good quality rifle, like Lyman or T/C. Good luck.

IF you are even considering shooting past 125 yards you are already looking at shooting sabot bullets. 100 yards is a long way with iron sights on a deer. Dawn and dusk is even trickier and further limits your range.

Personally when talking iron sights only you are talking ranges under 100 yards which places all projectiles on equal footing. Pick the rifle that apeals best to you.

It is tru that muzzleloaders were used for long range compettiion and sniping at ranges of 500 yards and more.

However, I and gues this is personnal preference, I would not shoot 150 yards at a deer with irons even in the best lighing conditions.

To each there own as long as the deer in not wounded.

As I read thru the responses, one thing becomes clear, they are all right at a particular point in time and location! My choice of 54 and larger, using patched round balls and real black powder, is a personal choice, not a requirement. I also use a rear peep sight, again, a choice. The choice of 54 cal or larger is based on the hole the projectile makes in the target, and the use of patched round balls, and open sights. Patched round balls don't expand a bunch, so starting with 54 cal means a good hit will have that as a base not have to expand to that to achieve 54 cal hole size. The slow twist rifling seems to work best with PRB's. The 1-48 twist is the compromise twist mentioned in ny other post, and will shoot both types of projectile but not optimally for either. Accuracy with a black powder rifle can be down right scary at long range, but a 308 outshines it for animal take down at long range most of the time. Many Black Powder seasons handicap the hunter with sight limitations, projectile limitations, ignition limitations, etc, one of the biggest is the sight limit. Put a scope on a black powder rifle, and shoot conicals, and you could very well outshoot any casual shooter with a modern rifle.

It all boils down to knowing your limitation, the season limitations, the rifles limitations, and acting accordingly. Open sights and patched round balls seem to be a happy mix. I always found BP to be a lot of fun, which also affects choices. I do think the 45 with a sabot or conical properly loaded is fine for deer, it is just not what I shoot most of the time. It is a great sport, have fun with it no matter which way you start!

I have taken many, many deer with the .45 flintlock with round balls. Also many, many with .50 and .54's. All but a couple of them went down in their tracks. The ones that didn't go down ran into trees and never made more then 30 to 50 yds. Wierd to watch a deer run headlong into a tree and peel off a pile of hair. the ball knocks them senseless. I was told by everyone the .45 is too small, can't prove it by me. Kills em quick. I used the flinters in Ohio in place of a shotgun and never felt undergunned.
Since I spent all of my deer hunting life with archery stuff and ball shooters and now do all of my gun hunting with revolvers, having shot over 320 deer, I see no reason to shoot far at a deer and find it no fun. I used a rifle several times and gave that up. Too easy and no thrill. The best part of going after deer is the HUNT, not the shooting.
I would base my purchase of a gun on what you intend to do. If you are going to hunt and shoot within 100 yds., get a ball shooter. Much more satisfying and much cheaper to shoot. You can shoot all day for pennys if you find some cheap or free pure lead instead of those expensive sabot thingys. That means you can shoot all year without breaking your wallet and it will make you a deadly shot to boot. What ever you decide, you will love it. have fun.