How about a nice old RoundBall...I spose you'd have to cut the choke off..if'n it's tight?(Choke, not Gun)
I have a new H&R single (wish that read H&H, Ha Ha}, rifled 20 bore that with a cheapish but fine brass custom mold(FRom a lad in Blighty}that shoots 2" groups all day from 50yds.
I load em soft, as no pressure info.
jesus thats a GRAND Pig..
I .ve heard they are in NH...but not heard exactly where,
nice shot ..JC
franc