In the A-Square Reloading Manual they show a test to show the effects of annealing on a case.

They took 10 .30/06 cases and loaded them each time with a 180gr Nosler Ballistic bullet using CCI-200 primers and a cahrge of 51.0 grains of RL15 powder.

The first five cases were never annealed. The velocities and pressures shown are the average for the 5 shots.

1st firing.......2673 fps & 53,900 psi
2nd firing.......2712 fps & 58,300 psi
3rd firing.......2715 fps & 57,600 psi
4th firing.......2741 fps & 59,700 psi
5th firing.......2764 fps & 62,300 psi

The second set of 5 cases were annealed after EACH firing and velocities and pressures are also an average for the 5 shots.

1st firing.......2681 fps & 55,900 psi
2nd firing.......2710 fps & 57,700 psi
3rd firing.......2692 fps & 56,700 psi
4th firing.......2702 fps & 56,200 psi
5th firing.......2708 fps & 57,200 psi

This test doesn't really adress things like splitting but I think it does clearly show that the brass in the neck is getting harder (increasing neck tension) and causing the pressure (and velocity) to increase.

They admit that annealing after each loading is excessive but do suggest after each 3 or 4 times to maintain as consistent neck tension as is reasonable.

Is any other conclusion possible except that annealing case necks is beneficial if you want to load consistent ammunition?

And if you shoot things like 416 Wby or Rigby a lot, then case life is worth preserving.

Some people have even be known to use Lazzeroni and Dakota brass, which I think last time I looked is slightly dearer than Remington bulk brass in 308

Mike

This was also reported by Rick Jamison in Shooting Times as a fact. I saw this ages ago and tried to duplicate their results as included in the A-Square manual. I also had a friend and poster (OKShooter) on several other boards who had an Oehler M40, to try the test using his pressure equipment. I could never get the loads to increase the velocity quite like the A-Square manual showed, nor could the guy with the M40, but there was a similar effect. What we both concluded was that there is an effect and increase in pressure (and velocity,) in the first two or three reloads. The velocity seemed to stabilize after the third and fourth reloads, as did the pressure.

What I did determine was that accuracy DID deteriorate and suffer after the first 3 reloads and that annealing WAS beneficial not only for maintaining accuracy, but to preserve case life by eliminating neck splits.