RE: Head space gauge
If you mean this,
https://www.hornady.com/shop/?ps_session=7520f964c626dcf603ce3e31244c8e67&p age=shop%2Fbrowse&category_id=4ffc0a8772783e83 440ac87ed0c3ee5b Then yes I use one. I have had one for a few years and I would be lost without it. It is the best way I know of to set up your FL dies.