Thanks RonSC, some of the Lyman/Cabela's/Investarms owners do report experiencing ignition problems with their brand new guns. It's usually always attributed to the nipple, once it's replaced with a better one the problems usually disappear. Since Black Powder is the easiest to ignite, switching to the APP ffg could become more problematic, but as you found in your TC, not necessarily.
However, while using the APP fffg shouldn't cause a major accuracy difference, one never knows until it's tried.
Plus it is a different make and model of gun., TC vs. Investarms, and not everything is going to be equal.
FForF, why not try shooting a couple of rounds with your ffg BP and fffg BP before you buy more powder?
At least you'll have a base line for comparison with any other powder.
If this is for hunting, the only shot that really matters is the first one out of a cold, clean barrel. And maybe even a second to simulate a follow up shot.
Then compare your 3 or 4 shots to your hunting accuracy needs and expectations.
And then decide if you want to shoot the APP.
Or else just save the BP for shooting patched roundballs.
I've been shooting the APP fffg out of my .54 inline with an #11 cap, and it's never failed. I shoot mostly Pyrodex otherwise, and if using Pyrodex for hunting, I load with Pyrodex P.
The are several reasons for using fffg or P. Substitute powders [besides 777] especially benefit from consistent compaction, and since fffg has less air space, it's compacts with less variation. Also, the smaller grains flow into the flash channel of sidelocks a little better to promotes good ignition. However, when using real black powder, it's not as clear cut, with some preferring ffg and others favoring fffg, but fffg is used by the minority among those who shoot the .54's.
Whichever powder or granulation you decide to buy or shoot, there's usually alternatives. If you did buy the APP ffg, and you wanted to better insure ignition, you could first drop 10 or 20 grains of some fffg black powder into the breach as an ignition catalyst, and then drop the rest of the load of APP on top it to make a duplex load. Some flintlock shooters do this.
Pyrodex P can produce good results too if you don't mind using a more corrosive powder. Like BP fffg, P produces a little less fouling residue compared to ffg or Pyrodex RS, but remember loads do need to be reduced by 10% volume to be equivalent, and maximum loads aren't always necessary for best accuracy.
