... I've been doing some chrono testing lately comparing the Hornady 168 bthp and the 168 Sierra Match King. The rifle is a Rem 40X with a generously throated 7.62 NATO spec chamber in its 27" barrel. In SIG brass loaded with 42 grains of recent production IMR 4064 the Hornady produced 2630 fps ...
I forgot to mention I shot the same load with the Hornady in another rifle, a Rem 700 XCR LRT with a 26" barrel. Its chamber/throat is tighter than the one in the 40X and is, of course, a different barrel altogether. Even though it gave up an inch of length, the XCR barrel spit them out 55 fps faster.
These averages came from two tests of twenty shots fired over an Oehler 35P so I believe they're reliable.
The chamber/throat in your rifle may be helping to build pressure with lower charges. Of course component lots vary, but I've shot many lots of H4895 through many 308 rifles and the speeds you're seeing would get my attention.
