Yes, they will work fine. I have used split leather (about 1/16" thick) for OPW. Squirt them with Murphy Oil Soap and alcohol for a lube before I seat them, and you can do them in advance. I put one on the muzzle and just cup it into the bore with a short starter and then seat the patched ball on top of it. Just don't shoot many of them through a chronograph, for they are a secondary projectile at close range and can damage the sunshades. I make them larger than bore size so they cup into the bore.