As I mentioned on another post, I've built a removable sight rail for my Parrott. I finally got it sighted in, and at 75 yards it is shooting 5" groups with 475 grains of ffg Diamondback and bullets from Victor3's mold (they weigh between 7.6 and 8.0 ounces). The group is centered on the bullseye and it has proven to be repeatable.
I'll try to post a picture of the finished rail with scope and also a picture of one of the punctured targets. By the way, it is shooting all the way through (across the grain) a round bale of hay. The holes through the target are perfectly round like wadcutters and the hole through the hale bale is also nearly perfect.
I'm very happy with the way it ended up.
NitroSteel