There have been many tests done by firing bullets of different calibers and velocities into compressed cardboard cakes.
There has been instances where militray FMJ ball loads traveling at high velocity simply pass through the cake, leaving two almost perfect holes with very little collateral damage. However, tests done with other rounds, including low velocity handgun hollow point rounds and defensive rifle rounds, showed that these rounds expanded significantly on impact, resulting in collateral damage to the insides of the compressed cardboard cake. The entry hole may be almost perfect, but the exit holes will be significantly larger, and may have a jagged look to it. Also, bits of cardboard may also be expelled, and the bullet itself, when recovered, would be found to have lower mass than before it was fired.
Evidently, expansion seems to play a major role in the effectiveness of different rounds.
When using muzzleloaders for hunting or self defense, one must be sure to use common soft lead, because these have overall greater expansion than other alloys available in the current markets. For example, the Hornady hard-balls and conical sabots are made with either antimony and lead or other forms of hardened material. While they were created for the purpose of penetrating heavy hides at long ranges, what they would do inside the target would be predictably milder than using a patched roundball casted from pure soft lead. HOWEVER, on the other hand, if you are hunting bison or bear at extended ranges with a muzzleloader, it will be foolhardy to use a patched roundball, because it might expand so rapidly that it will lose most of it's energy upon contacting the hide, and probably never even penetrate enought to create significant wound channels. It might never even penetrate at all.
American soldiers stationed in the western frontier in the years prior to the War For Southern Independance reported that their .36 Navies firing the round ball had alsmost no effect in stopping big game, while a .44 Walker firing the "picket bullet" is extremely effective against bear and buffalo.
HOWEVER, the same picket bullet used for self defense against a violent repeat offender who just broke into your home and is threatening to execute your wife and children might not cause significant injury as to stop the aggressor. When the conical was used against heavy game, it already started expanding when it came into contact with the hide, and continued expanding when it went inside, thus creating terminal wound channels. The same round used against a human assailant might not work as effectively, unless he/she is wearing a heavy jacket that will enable the bullet to expand on contact and thus produce a terminal wound channel once it penetrates the actual body.
In the above-mentioned self defense scenario, when seconds meant the difference between statistics in the local crime report or a story of remarkable strength and survival in the Armed Citizen section of the American Rifleman Magazine, the patched roundball will work the best. Upon impact with the assailant, it will expand violently and create a terminal wound channel that will stop him/her IMMEDIATELY.
While bullets of one type will work effectively in one given scenario, it does not mean that it will perform the same way in a different scenario. Likewise, while the simple round ball may produce devastating results upon human assailants, or medium sized creatures such as jackals, I wouldn't use the same round ball ammunition if my quarry is Alaskan Grizzly or Plains Buffalo.
Therefore, we are kind of in a dilemma right now. The best thing to do is to assess your situation and determine what caliber/type of ammunition you will need. You wouldn't go out and make an arrest on a drug den while carrying a .22, unless it is a .223. Likewise, you wouldn't use a .44 Magnum while hunting for squirrels.
