If you are referring to the green anodized ones, I love them for reloading. They are easy to reload, hold enough Bullseye to do the job, and the vent plugs are easy to replace. I use a bit of cotton string to fit that closing plug (the piece with the primer) in place. To reload them, replace the primer, replace the vent hole burst disc, load your charge, hold the cotton string (about the thickness of one of the inner strands of 550 cord) (you could use an inner strand of 550 cord…) on one side of the plug and start it in the casing. The string will make the plug fit tight and not back out after you load it.
The powder charge will depend on the weight and type of projectile. 3 grains (reloading scale) of Bullseye is good for rubber batons. 6-7 grains for 781 projectiles. 5 for pyro air or ground rounds where you are lighting fuse with your launch. GROG