I have the Yankee Hill phantom 30 cal. been shooting it for a year on a 5r 308 and its butter. Just finnished a build of a 300 wm 5r and will use the same can on it . For the money its great, but if I could go back and get the titanium one for some weight savings,,,, I would. my 308 feels like a 22 rifle with the can on it and with a berger 175 otm and lapua with 44 grns of rl 15 i can reach 1200 yards (and hit the steel target to!) I tried to attach a pic of the 5r 300wm. Just finnished the build!
Also I shoot my cartridge at 2.815 for mag .length
I have never measured the headspace. Both of these loads have bullets that like some jump.. look up a guy named bryan lytz. He work for beger and wrote the bible I use. Or you can google secant vs tangent ogive. I for get which one it is but one like to be close to the lands the other it doesn't make a diffrence.... the round marked vld (very low drag) like being a few k off lands. With bryans hybrid ogive bullets you get the low drag high bc without finniky seating depths