We have to crop our tups' horns quite often - Rough Fells. It's quite normal unfortunately, they've been bred with horns that are too tight.
We use a horn wire too and it reduces the bleeding. Even if it does, it doesn't seem to bother them that much, they're straight into the feed afterwards and seem to forget about it.
We have sometimes got away with 'shaving' the inside of the horn off - we do that with a pruning saw, but have to be very careful about his eye then. We tie the other horn to a fence post and then have someone pushing him against the fence with their body and holding his chin.
Just as Fleecewife says, keep an eye on the horn - I knew someone have a tup lose an eye from the pressure cos he didn't do anything soon enough!