Bushmaster:
My chrono and my 20" bbls.
With Federal cases, Federal #210 primers, seated to cannulure and crimped.
Remember in Georgia, 90's temps are the norm 6mos of the year.... So, in September, temps are still in '90's in the afternoon, in the shade.....
so that might be part of the equation.
I have an Alliant manual circa early '90's that indeed does list these velocities from a 20" bbl. Later manuals list 24" bbls.
Not all lot#'s however will break 2,400fps w/150gr bullet.
I've found that factory loaded Winchester 150gr HP run 2,275fps and have 35.6gr of what appears to be Win748, which my rifle duplicates. However with a max load of 37.5gr of Win748, and temps above the mid '70's, it too will break 2,400fps fro a 20" bbl. You only get approx 25fps from each additional inch of bbl with the .30wcf.
My brothers load of 33.5gr of H4895 runs 2,325 from both his and my chrono's and is from a 20"bbl M94. Again, temp's in the mid '70's deg.Farenheit.
I've also gotten 2,300's fps form 170's from both 20" and 24" Marlin .30wcf barrels with H414. low with the 20" and high with 24"bbls. Old data from the late 70's and early 80's however......
I'vd even gotten 2,650fps from a 125gr Sierra HP from a 24" Marlin M336C and early lot#'s of H322. Later lot#'s only get 2,550fps or so. Later lot#'s are somewhat faster burning than the early surplus quatities....
Never say Never !!!
