Modern Reloading II

[milkman]

I have been re-reading Lee's Modern Reloading second edition, and the section on using the strength of the bullet, or as he calls it, the ultimate compressive strength, in psi, to select a load based on chamber pressue, in psi.
As Sylvester the Cat says "That Thssssounds Logical". Has anyone used it? Does it work?
If you had a 30.06 with a 110g gas check bullet of the proper diameter for the barrel, lubed with felix lube, 29.9 BHN, which correlates to 38k psi, could you REALISTICALLY push it to 2900 fps, with no leading and with accuracy as he states? Does it work with less extreme examples?
The pressure/ velocities for heavier bullets with lower hardness numbers seem more down-to-earth, but maybe its because I'm more used to seeing them.

milkman

[felix]

Milkman, accuracy wanes above 2400 for the most part using a typical lead boolit. Mostly this is because the boolit begins to deform at around this velocity, both inside and outside of the barrel. Tougher boolits, like full lino, or some lessor boolits with copper impregnation instead, will stand a better chance of making it to 2700 with some accuracy. Jacketed boolits as you have probably experienced tend to fall apart at around 4000 or slightly higher. Now, if you really step on a lead boolit, and this depends on the accelleration curve for the most part, a typical lead boolit can be compressed to fit the barrel extremely well allowing a fair group at 3000. But, for the most part, assume 2400 is max for run of the mill boolits. ... felix

[Leftoverdj]

Milkman, I have not tried any of the extremes, such as the example you cited. I suspect that other, unaccounted for factors can come into play. I have been using Lee's charts and theory within normal cast bullet practice and they do get me to a satisfactory load much faster. They let me make a much more informed guess at where to start.

[MOA Shooter]

Given sound loading practices, the primary determining factor in the cast equasion is the rifle barrel. No matter how well aligned your 'ducks' are when you close that round into the chamber the barrel has the final say as to consistency of accuracy. The best barrels will allow cast performance at those speeds and psi... the average to poor iron most casters shoot will not.