When I started MLing in ‘73 (there was no such thing as “modern MLers then) I used a conical and a whole bunch of powder. I even used the same on deer and hogs. Then I got involved w some folks shooting patched round ball (PRB) and moved in that direction. Now it’s only PRB. I got to wondering why anyone used conicals, I mean if a .243 opens up to 1/2” then why any 1/2” hole through the boiler room won’t do as well?

Yea, if that’s what the gun shoots best is a good answer. Can’t see open sights need a scope, another good answer. Hunt out west in wide open, come on bow hunters take prong horn out there. Cleaning is too much trouble? Not if you know how.

I mean from a terminal performance/lethality perspective. What’s the allure or perceived advantage of MML with a conical?

In most of Texas there’s no special ML season so I’d just get a single shot .45-70 or some other cartridge gun. Oh hell, a .30-06 bolt gun, that’s old school compared to an AR in some new tangled caliber.

Just me just wondering.

With the 45 cal Kentucky rifle and it's 1:60 twist round balls are the only thing that is accurate from it. It kills deer but most of the time the round ball does not exit where with the conical I have yet to have one stay in a deer. Mostly these days I use sabot and handgun bullets in Inline ML but sometimes take out the Kentucky.

The original conical bullets Minnie balls were mostly for speed of loading in military applications

If a pass through was a high priority a .50 or .54 would have been a proper choice.

I have everything you listed covered. I have killed almost as many deer with a patched round ball as I have a centerfire. My biggest Buck ever was killed with a patched round ball. That buck's legs crumbled under him He did not even fall over when I hit him. I did everything backwards from most hunters. Most people start with rifles and work their way back to muzzleloaders or bows. I started with a longbow then compound and on up to more modern from there. When Thompson came out with the Scout, the first inline muzzleloader if I remember right, I picked one up in 54 cal to go with my 50 cal percussion rifle. It has a fast rate of twist so I have always had to use the Thompson Scout with conicals. I mostly moved on to centerfires, but I do often hunt these days with a smokeless muzzleloader using sabots and pistol bullets. Since you mentioned single shots. One of my rolling blocks is a near 150 year old Swedish Husky converted to 50-70. I have never taken a Deer with it, but did make up some black powder hunting loads for it and sighted them in for any time I wish to. I could hunt with any of the above or any of several more modern rifles. Why limit myself to one type or one rifle? I like to change it up. I could be using a bow one day, crossbow another, a muzzleloader , or a new or old centerfire. So don't worry, I'll break out the old Powder Rifle rifle with it's 1/66 twist and patched round ball on another hunt sometime. Now I do always regret not picking up a flintlock to round out my muzzleloaders accumulation. Problem is between my collection rifles and my hunting guns I already have over 200 long guns. I used to have a plan to take a different rifle from my collection every year, learn it's capabilities and limitations, and then hunt with it at least once during season. At my age it will be impossible to accomplish with just the ones I have. So I don't pick up new additions very often these days. But a 45 cal flintlock Pennsylvania rifle or similar long rifle with a slow twist for patched round balls has always been on my wish list.

I have one 1:24" twist .54 caliber. It is way more accurate out at 100-yards with full bore conicals. All my other cap lock and flintlock rifles, and a smoothbore use PRB's. The most accurate of them is a .54 flintlock shooting PRB.

I shoot a patched round ball in my .54 Hawken. Have you ever recovered a round ball? It is quite a bit bigger than .530 I tried all kinds of conicals and sabots and always went back to the round ball due to my gun shooting them more accurately.

Same here in my 50 cal Hawkin, scary accurate with patched round balls.