Wow, a 7 year old thread!
By then (June, 2012), we had already been messing with contemporary (1:17/18" twist & zero free-bore) 30 BRs for about 13 years - during this entire interval, two attributes [almost] always "work": 1) adequate neck clearance; 2) more neck-tension. A third, somewhat more variable attribute: seating depth - JAM, or, "soft-seat" (aka hard/full jam) often strops the blade!
I've enjoyed the opportunity to assist dozens of people find the tune for their first 30BR - I have yet to observe an instance where using 0.002", or, more total neck clearance, & a bushing 0.004", or, more, under the loaded-round neck diameter degraded precision. In every instance, when the bushing is 0.002" to .003" under, and grouping is somewhat disappointing, a 0.004" under bushing has, "turned on the lights".
Sometimes, lighter grip works, however never fear more tension - you are NOT going to wreck your brass! When setting neck clearance, always measure the loaded-round, across the heel of the bullet. For thirty caliber cartridges, I have yet to see less neck-tension work better.
Though my original tooling continues to to work, and is compatible with my particular Redding Type "S" die, as I have stated in other threads, if ordering a new reamer today, I'd opt for a .331", or, .332" neck diameter, and
specify a minimum web (.200" ahead of bolt-face) diameter of .472". Shooting my own FB bullets - usually featuring a .3086" "pressure-ring", I continue to turn for a loaded-round neck-diameter of .3282" (not quite the 0.002" i preach
), which results in a calculated neck-wall thickness of 0.0098" - this has worked so well, with the old Skip Otto .324" carbide bushing, and my reamer, I'm not changing anything.
In the contemporary 30BR, Ronnie Long dreamed up a winner.
RG
edited time reference.
