Yes, it is.

Friend of mine had me chamber a .308" groove dia. barrel to chamber standard .303 factory ammo. After doing that, he found it didn't like the 220gr. Hornady's he wanted to use, but shot right around 1/2" with 150gr. Hornady Interbond bullets. He used that load, running 2,750fps for his long range deer - WT and Muley bucks, both taken at 100 to 110yards, as well as his 120yard moose and 415yard bull elk. All, 1 shot each. That's one fall's hunting - lots of meat in the freezer for family and local relatives.
150gr. .308's and .303's, if a decent bullet, do the job if placed correctly. They will not fail. He told me the elk took 3 or 4 steps - he wasn't sure, then dropped.
Seems my (& his) preferred heavier bullet weights were not needed - at all.