53 grains is a compressed load. I compress all my loads.
Forgot to mention 3 helpful tools. Volume measure, drop tube, and compression die.
There is a lot more to loading black, than modern. I bought my volume measure (now dont use it) It was only $5.
The compression die and 45 cal ram was $30 on sale from Cabellas. I made my own drop tube from $3 bucks of wood, and a $12 hunk of brass tubing.
Using modern powder is not any safer, just easier and nicer clean up.
I was given 2lbs of pyrodex, and have a real black stash for my flintlock. So trying it was worth the extra few tools.
R-7 is a hotter, cleaner powder, IMR-4198 even better. Unless you have IMR-4895, stay away, its darn accurate, but a very dirty powder. I use it for my heavy boolits because I have lots of it.
Only reason I use R-7 and not IMR-4198 is it works in my 30-30s also.