I would be checking throat diameter and muzzle wear if you are have big groups at 100 yards. Not that a carbine is a tack driver but 3" and less at 100 yards is common for the carbines I have loaded for.
At 100 yards bullet coefficient is so unimportant nose design really has little value except to impact. I personally like flat nosed types as they make far better "thumps" on impact. As long as it feeds reliably and is fat enough for your rifle any bullet of rpoper length is going to work.
Mike in Peru