Hi Pacanis and WELCOME to the forum!
I had a Pedersoli Brown Bess "Carbine" I shot competitively with .735 cal. round balls and shot. My bore measured .753/.754 and
ELEVEN (11) gauge cards and wads were a perfect fit for that bore size. I never had time to develop the best shot load for it, though, so I will leave suggestions for that to others.
OK a little history of the Bess is in order. The ORIGINAL British Ordnance mandated bore size was ".76 cal." or what we would call .760" today, BUT the actual approved period bore sizes ran from .76 to .78 cal. because they did not have precision measuring instruments nor the ability to hold tolerances any tighter back then on such large quantities of arms. Also, the ORIGINAL British Ordnance mandated Ball Size was ".69 cal." or .690" BUT that was inside the paper wrapped cartridge. Unfired Original Balls for the Brown Bess have been excavated all over America, though, and the actual sizes ran from .690" to .720" with .710" size the most common.
Since your bore size will likely be similar to mine at .753/.754 " (though you should verify that with precision Calipers), the .69 cal ball mold you ordered should work very well for making paper wrapped cartridges, should you wish to do so.
OK, I admit I'm somewhat obsessed with getting the most accuracy out of my guns, because I want to know when a shot goes wrong, it is my fault and not the gun. I don't expect a smoothbore to shoot as accurately as a rifle, but I want it to be as accurate as it can be. My accuracy load in my Pedersoli Carbine with the .753//.754 " bore was a .735" ball, a well lubed ticking patch (I take my calipers inside the Fabric Store and bought the "thinner" ticking that was around .014" thick), and 70 grains of Dupont FFFg powder. Your powder charge may/will vary with any other powder for the best accuracy in your Bess.
I HAD to use a BIG short starter with the above tight patched ball load similar to the one linked below. Remember I said I was somewhat obsessed? Grin. Well, I took a .735" lead ball, some 150 grit emory cloth (sandpaper for metal) and put the abrasive side of the cloth next to BOTH brass ends on the short starter. I used the ball to push against the cloth while turning it to reshape the brass ends closer to the actual size of the ball. OK, so why in the Heck did I do that? The sanded/reshaped brass ends did not dig into and leave a ding or ring on the ball when using the short starter over the sprue. I think not having the lead balls dinged/ringed allowed a little better accuracy, though I admit I'd be hard pressed to fully document that. I was taught to do it on my rifle short starter brass ends, so I did it for my Brown Bess short starter.
https://www.trackofthewolf.com/Categories/PartDetail.aspx/118/3/ST-8
I could absolutely count on the fact at 25 yards (Offhand) that my ball would split on the axe head and each piece would shatter the clay pigeons hung on each side. At 100 yards, I could hit a one gallon milk jug 8 out of 10 times from the Offhand, but the gun could have done it at least 9 times out of ten. I wasn't as good of a shot then as I learned to be later.
OK, this is running long and so I don't lose it, will continue in my next post.
Gus