Reynolds, Thats very interesting. The Lee 310 would not stabilize in my barrel, made the prettiest keyholes one's ever seen. That may have had something to do with my barrel being .432 I never tried the 310 after I found that out. The Hornady 300 XTP shot just fine however, and if yo invert the data you've posted, it is exactly as I was seeing with the Speer 270 Gold Dot and the 300 XTP...Go figure. I'm not sure I take the lead is more slippery than jacketed in every case. There is evidence that in 45 ACP, lead can run up pressures faster than jacketed and is not always as fast. Not argueing one side or another, just stuff that makes ya go Hmmmmmmm.....
Edited for spelling