that's probably helpful to know the makes. the tightest is the jelly head at .660, two undertakers at .665 one ported one not. tightwad at .670, trueglo at .675 and a remmie exfull turkey that measures .686. which is way to open to through anything smaller the 4's past 35yrds.
reason I ask is that several of these state not to use steel. would that also include the hard HTL loads?