That's probably a Seneca butt plate too. Looks like they cut the comb down at the heel
end to fit it.
First of all you should shoot them as is, get to know them as they are. I don't mean
one shot each either. Shoot them all day and play with the loads until you've wrung
out and found out the best they can do. You might find that you like them just the
way they are.