In all honesty a Fast Twist Bullet Barreled Flintlock would probably be a lot fun, Definitely be a challenge! If i was gonna try it i would work from a ROCK SOLID bench and i would use a good Sand Bag setup, start at 25-50 yards and work away on a load til i found what the rifle liked best, The most important thing for me would be training MYSELF to ‘Follow Through’ after the shot, Training myself to follow through a Gauranteed slight hangfire would no doubt be the biggest challenge for me personally. Understanding the Lock and keeping it ‘Highly tuned’ for super fast ignition would be a must, Hardening of the Frizzen, the best flints to use, how to Nap them etc. All in which i know NOTHING about LOL! Except for reading and watching Videos. There is a guy on Castboolits that goes by rfd, Great guy!! He and i visited about every morning When i was on CB, Rob is a VERY good guy, and super knowledgeable about Flintlocks, if you needed help tuning your lock, types of flints, how to Nap them, hardening the fizzen, etc. etc. i would advise getting in touch with him!
With the right Paper Patched bullet/Load Combo it would really come down to how good are you at doing your part? You could be confident knowing the barrel is VERY CAPABLE!