Re: "Jamming" bullet into the lands?
"Benchresters and others may use this so-called "jam fit" for best accuracy,"
That's correct...but only for some of the BR crowd. Not all of them do it and the primary benefit isn't to gain "better bullet alignment" as it's often stated. They seat bullets to the lands to retard movement until the pressure curve is steep enough to get a good burn.
Most, if not all, serious BR shooters have very tight necked chambers that demand their case necks be thinned quite a bit to even chamber. Bullets seated "normally" in thin necks may have too little start resistance for the powder burn rate to build properly for best accuracy. Few sporting rifles with normal (thick) necked cases need that start resistance and most factory (SAAMI) chambered sporting rifles shoot best from .020" off the lands to as much as 5 -6 times that much.
Bottom line, BR shooters load for their rifles. But we don't have BR rifles or components so attempting to duplicate their methods without understanding why the he77 we're doing it not only may not help, it may actually hurt our results.
That said, the light ogive surface marks at lands contact mean nothing to the bullets so jamming into the lands isn't likely to do anymore meaningful "damage" to the jacket than the die seating plug does.
Last edited by boomtube; 12-04-2010 at 11:13 AM.