Well I have shot both and I guess the dividing line is the jump from percussion caps to shotgun primers. At first I thought what a great idea. Now not so much. Oddly the bigger blast of shotgun primers causes problems with some subs like 777 and Pyrodex. Shooters World MPB does it but not as bad, easy to remove with one wet patch. The famous crud ring. Never had this problem in either of my traditional Hawkins style rifles or my FireHawk. Plus with a capper putting a percussion cap on a nipple is far easier than getting a shotgun primer in it's hole. With the Hawkins and the FireHawk I don't have to remove and clean the breechblock or it's threads either. This said the two rifles I have that use shotgun primers are both accurate reliable rifles. In fact before Covid and the percussion cap shortage I had no real reason to get a ML that used shotgun primers but had a 50 caliber Encore barrel anyway. Now my Grandson uses his for all his hunting even though he has access to many modern rifles. This year I am using my percussion capped fired rifles until my #11's run out again.