MAGAZINE

THE HANDLOADING BENCH308 Winchester Rides Again Part 3By Laurie Hollandguilty of giving a dirtier burn than extruded types. Thecause is the absence of the tubular form’s hole up themiddle that causes the kernel to burn outwards as wellTo Laurie’s surprise, the SRP ‘Palma’ brass version (right) of the 175gn BTLR + H414 ball powder came out on top despitetesting in cool conditions.better in this role as well as being viable in F/TR. Itspreferred rifling twist rate runs a bit tighter at 1-12”though.Ball PowderThat left one more thing to try with ‘Palma’ brass– ball or spherical powders, again using the 175gnBerger BTLR which the barrel obviously liked. Putmost 175gn or heavier bullets through a QuickLOAD.308 Win Charge Weight Table run and you’ll findHodgdon H414 / Winchester 760 (same powder,different bottles) at or near the top of the predictedvelocity listing. This is a double-base propellant that’sbeen around forever, has a slightly faster burning ratethan the 4350s and Viht N550, and is well suited tomid-size cartridges because of its density. I usuallyavoid ball powders as they’ve been traditionally foundas from the outside in. As the ball kernel’s surface areacan only reduce as it is consumed, this form producesa ‘regressive’ burning behaviour (high gas productioninitially reducing as the charge is consumed). Tocounter this, a thick coating of non-inflammable‘deterrents’ is used to slow the early-stage burn, butthese chemicals are left behind as fouling, usuallybaked on hard thanks to the double-base propellant’sflame temperatures. Another consequence of heaviersurface coatings is greater difficulty in igniting thesepowders, hence the common advice to use magnumLR primers. Actually, ball propellant technologiesand ingredients have moved on a lot over the years,reducing these and other alleged downsides. However,if there is any doubt about the SRP’s ability to light upa heavy charge in .308W, it would likely show up withthis powder.66