I've measured WTBY, RP, WW, Fed and Norma - all have showed over the standard .007" headspace measurements. As far as I'm concerned, even .005" or .006" is excessive, when it's a simple matter to do it all right in the first place.

I haven't measured any recently as I no longer shoot any belted magnums, my last .458 and ..375 being sold. In the .458 2" stuff, I used several makes of .338 brass, RP.350 Rem Mag brass as well as WW .458 brass. All brands had cases over .217". A few cases even went to .224", yet all chambered, but those 'extra' long ones shouldn't have.

Perhaps newer brass is being held to tighter specs. Perhaps there was a clamp-down by SAAMI 'whoever' they are.

I still look for reasons to not use or circumvent using belted brass as the belts are only needed on straight cases. They also add no useable strength to the case.