The Lymans are a straight on fit while the Hornadys are a bit thicker around the lip to provide a crimping effect when seated and run through a sizer. At least that was the situation several years ago. Also, Hornadys are a lot cheaper the last time I looked.

Finally, and I have no way to verify this, but I read that Lyman checks are made by Hornady anyway...


Gunnery, gunnery, gunnery.
Hit the target, all else is twaddle!