Did you check CVA's website for a online manual? They had them the last time i was there in PDF format. As Ron said, the OEM plug works ok with loose powder excluding Blackhorn209.

Both CVA and Western Powders offer what is called a Blackhorn209 breach plug. You need to properly "seat" it once to mate it to the barrel. After using the tool to seat and remove the new plug one time, you no longer need any tool for the plug. Western supplies a tool with their plug to make it easy, plus a tool (drill bit) to clean the flame channel and some o-rings for the primer pocket.

Ron's modified OEM plug works just as good, actually better than both and it will basically last indefinitely. You just replace the $4-$5 vent liner when the flash HOLE gets too large. The removable vent liner replaces the fixed flash HOLE and also makes it a little easier to thoroughly clean the flash CHANNEL.

BTW a 24" barrel is enough to burn 100gr loose powder charges or even more. Some guns even shoot hotter charges of BH209 very well in shorter barrels. Pellet loads may not but i quit using pellets years ago. Its much easier to work up a better load with loose and loose powder is cheaper per shot than pellets.