5R, that Sierra 180's not all that great for ranges past 600 yards from a .308 Win. case. Back in the '80's, Sierra changed that bullet's longer boattail (exactly like their 190 and 200 HPMK's) to the shorter one like their 168's. The new version never shot well at the longer ranges just like the 168 HPMK. All the competitors cheered when Sierra used their longer boattail on the 175 HPMK bullets.
That aside, it's still a great bullet for use up to 600 yards. I've still got about 800 or so left from a box of 1000 I got some years ago. These are a select lot that tested at 100 yards in the ones (under .200") at Sierra's California plant. In my barrels, they easily shot 1/3 MOA at 300. I probably ought to sell them as I don't use 'em any more.
One can put 44 grains of IMR4064 in a case with a 180 HPMK if they use a drop tube or jiggle the charged case a bit to settle the powder lower.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master