I recently acquired a uncompleted kit rifle from my late brother. He had finished the stock very nicely but failed to install the sights and the butt plate was missing. It appears to have been this way since the late 70's when he started it. I obtained a butt plate from Dear Creek and managed to get the sights installed even though the dovetails were a bit oversized. A shim in the rear and a couple peens on the front sight base and we were good to go.
I don't think he had ever shot it. The starter kit still had the balls in an unopened bag and he had no powder around.
I decided it needed to be finished up right to honor his memory. I obtained a period correct sling and blinged it up with some beads and feathers. I polished as much of the brass as I could and I set about finding powder and caps. It is a side lock percussion rifle replica of a Kentucky Long Rifle in .45 caliber.
I researched if I could convert it to use 209 primers rather than caps which have a nasty spray of dirty residue that gets all over the outside, not to mention the sparks that fly out.
I found a contraption called the Mag-Spark
http://www.warrencustomoutdoor.com/mag-spark.html which replaces the nipple and allows you to use the 209 primers.
If you have a percussion rifle and are not locked into having to use caps because of being period correct, this is great!
It achieves much better and cleaner powder burn and is very reliable in any weather.
At about $30.00 it is a bargain.