Originally Posted by Jordan Smith
Originally Posted by drop_point
Originally Posted by Jordan Smith
Originally Posted by Al_Nyhus
For a 7-8 twist set up to the longer bullets, the throat length will be excessively long for best accuracy with the shorter bullets.

And to do a 7-8 twist with a short throat for the shorter bullets is double backwards.
Al,

Can you explain the above quote? Long, sleek bullets have an ogive that is closer to the case mouth compared to short, blunt bullets. Long bullets typically require a shorter throat than short bullets. If anything, a rifle throated to long, sleek bullets would necessitate light, blunt bullets to be seated quite deep in the case neck to avoid a jam into the lands.

It has been my experience that longer bullets require longer throats, not shorter.
Of course, the descriptors "shorter" and "longer" are too vague to make any definitive statements. I agree that the shortest bullets made in a given caliber will require a shorter throat than the longest bullets made in that caliber, assuming similar seating depth in the case neck. Let's say that the ideal setup includes two assumptions: first, that the magazine doesn't limit OAL within practical limits. Second, that the ideal seating of the bullet is for the base of the bullet body to be seated just above the shoulder-neck junction of the case. Given two bullets of equal weight, the longer, sleeker bullet will require a faster twist rate and a shorter throat than the short, blunt bullet. If we drop enough weight and length from the short bullet (or change its shape enough), I agree that there is a point at which the longer bullet will require a longer throat than the short bullet.

Generally speaking, for long bullets to fit within magazine constraints, they have to be seated deeply and contact the lands at a rather short BTO length.

My F-T/R .308 has a 0.170" throat for shooting 200gr Bergers. A PALMA reamer might be around 0.050". If I recall correctly, most chambers will be in the 0.085" range.

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