If you search the forums there is a few discussions on them.
I use them in a 1:70 twist 50 Cal Green Mountain barrel (36" long).
They are "heavy" weighing the same as a 54 Cal roundball (240'ish grains).
I fire them over 80 grains of FFF Goex. My shoulder tells me that they are "less fun" than firing a 50 cal roundball with the same amount of powder.
Being heavier they drop quicker during flight so if you are sighted for and used to shooting roundballs they are going to hit "lower" after about 50 yards and the further they fly the more pronounced the drop will become "compared to what you would be used to".
Because of that the rifle I use them in is kept for shooting them exclusively.
Right out of the package they are "lubed up" with whatever goop Hornady coats them with. Some have noted it dries out, I haven't experienced that - keep them sealed in the plastic bag they come in then sealed in a ziplock bag.
I typically hunt at bow range - so 35 yards is "out there" - I use that rifle and the PA's as my 75 yard gun when hunting an unfamiliar area where I don't know the terrain etc.
These were concocted by Hornady specifically for the flint deer season in Pennsylvania hence the name. There was/is a market for guys who typically "don't shoot" muzzle loaders and they are the perfect load for the Traditions PA Pellet Flintlock. Even designed specifically for it's 1:66 twist - that's the "target market".
(in conversation with a Hornady tech he told me that while they were designed for the 1:66 twist that they had observed good results from 1:72 up to 1:48)
They are really just a rip off of the "no longer produced" Ball-ete from Buffalo bullets - half round ball half conical.
They group no better or no worse than a round ball at a given distance if you do proper load development. Besides, being a hunting round the "group" means nothing - you typically only get one shot - it's either on target and you get a kill, off a bit and you are tracking for hours or a clean miss - so as long as you can put one in an 8" pieplate at your chosen range not much else matters.
If you are shooting them because you feel "under gunned" with the 50, simply moving up to a 54 shooting a roundball will give you the same terminal ballistics.
These do have their place, it's just a very small niche. I got about half a dozen boxes for nothing so "for me", as a hobby builder, justified building a rifle "just for them".
That rifle rarely sees daylight. I now hunt deer with a 38 round ball after retiring my earlier 45 and 40 caliber Bambi rifles. When I know that I can take down a deer, at my hunting range, with a 92 grain round ball I don't see much of a need to punish my shoulder with 240 grains of PA and 50% more powder
