Originally Posted by woods
This statement is half wrong and half right and the first part is an opposite of the second conclusion. Off of the Barnes website:
"These grooved rings act as relief valves as bullet metal flows under pressure while traveling down the bore. Instead of flowing from the front to the base of the bullet, the copper material expands into the grooves. This results in reduced pressures and less copper fouling. Reduced pressures mean the bullet can be safely loaded to higher velocities."
So the all copper bullets develop LOWER pressures with the SAME AMOUNT of powder but you do nee to add more powder to get the same pressure value.
Not trying to bust your chops, just didn't want anyone getting confused.
If you believe the 'hype' that Barnes is selling everyone, go right ahead and use the same loads with their bullets as you are for conventional bullets. Compare velocities with a chronograph and we'll see what's what in the real world.
Getting back to the original thread, powder doesn't cause any of the symptons described or shown in those photos, powder dgredation results in hangfires, no ignition or complete detonation and blown rifles, this is caused by a powder charge that hasn't produced the correct pressure for normal ignition as I, boomtube and larrywillis described.
Also, loaders_loft, Nosler say not to exceed the middle charges because pressures would be dangerously high if you exceeded them, not because they produce higher velocity at lower pressure, the only way to achieve any velocity with any bullet is by the pressure developed, not by some 'magical' bullet.
I own a pressure/strain gauge which I use on every load I test, and it will tell me exactly where UNIFORM ignition is happening in each load string, normally on average about 5000psi below max pressure, but velocity is normally only 25-50fps slower at this amount of pressure reduction.
A long throated rifle will not cause a dent to form on the case because the neck has already expanded to fill the chamber just as the bullet is released from the neck, therefore creating a seal, just as it does in normal or short throated rifles. Nearly all 22-250 rifles have long thtroats and I've never seen a dented case unless there has been a problem as above in the original post.
They are caused by low or inconsistent pressures.