Doulos - that is correct. The slow twist demands higher than typlical 'whitetail killing speed' to stabilize the round ball. To get that stability, requires more powder and more powder means higher recoil but delivers substancially flatter trajectory. Many think the ball does not need to be stabilized like a bullet demands, but that thinking is incorrect.

The larger bores are definitely mean for heavier and tougher game than deer - moose, elk, and the big bears, along with African species.

When you slow the twist, you must increase the speed. The shallow rilfing, which loads easily even with a hard ball which is necessary for the deepest penetration, does not stip due to the slower twists.

The increased speed flattens trajectory, giving an otherwise large bore gun a point blank range of 130yards - to get that with a heavy round ball for killing large game is a wonderful bonus.

That sort of trajectory is not possible with an type of slug in the same bore sized rifle.

The charges needed for get good accuracy in slow twist barrels will have many of todays shooters wincing at the recoil.

My own 14 bore, even though having a relatively fast 66" twist with .012" deep rlfing, demands 140gr. of more 2f to shoot accurately with it's 482gr. pure lead ball. If it did not have the .012" deep rlfing and I did not use a patch combination many would falter at loading, it would not shoot as well as it does. I know, as I've extensively shot this rifle with ALL powder charges and patch combinations at all ranges to 200yards.

I have never witnesses a more accurate muzzleloading hunting rifle than that one. It still consistantly shoots into from 1" to 1 1/2" for 5 shots off the bags at 100 meters. Not many guys here will shoot my "Gentle Lady" a the second time, yet even with my shoulder injuries, I can use it on the bush trail quite easily, shooting steel targets - I'm used to it's recoil & the way it recoils, which is quite soft - I feel. It's an English gun of the 1850 period, the epitomy of a hunting rifle design. The later guns follow it's traits very closely.

I know that reducing the bore size from 14 to a one ounce ball, ie: 16 bore, will allow me to shoot the heavier charges needed for 'guilt edge accuracy', and still handle the recoil. I am also looking for an 80" to 85" twist with from .005" minimum to .008" at the most, rifling depth.

The slow twist allows (and demands) heavier charges, which flattens trajectory; The slow twist also allows shallow rifling allows using hard alloyed balls for heavier game, with normal cloth patches. Each 'change' humors the other. The higher charges needed is also humored, as we want higher speeds to shoot flatter trajectories over unknown ranges. The exact range is not necessary- to know it's just over 100yards is enough. Then, we use an express sight with a coupld leaves, file them in for specific ranges.

Later styled American rifles with narrow butt plates, and much drop at the comb and heel are NOT suitable for this type of barrel. Would one of these barrels be a good replacement on a Hawken rifle? I'd definitley not recommend that but then, that's why the English design prevailed in heavy calibre rifles ever after.

NOTE! If the question is: do I need a Forsyth-Principal barrel to shoot Eastern Whitetailed deer? - the answer is definitely no.
If the question is, do I need this type of barrel to shoot Wester Mulies or whitetailed deer out to 225 yards? - the answer is a definite and resounding YES! The squib loads that will kill Eastern 50 to 60yard whitetails all day long in the bushes and smaller fields there, are useless at longer ranges over unknown plains or draws up valleys where stalking closer than 200 or 150yards might not be possible. We're talking .62 cal. or smaller, here, maybe down to .54.

In my honest opinion, of course.