Annealing

[Norm]

My thought on the subject.

The accuracy potential of annealed cases V’s non-annealed cases is a hard one to quantify and test for.
Some here have mentioned that a slight improvement in velocity ES is possible and that may that may contribute to improved accuracy. But I think there is more to it than that.

As cases are fired multiple times the case neck brass work hardens and the tensile strength of the brass increases. If you do not alter your neck sizing bushing the grip that the neck has on a loaded bullet will increase as the tensile strength of the case neck increases after each firing.

So long as you batch your cases, all loaded rounds should have a similar grip on a loaded bullet.
However if you mix your brass up with cases that have been fired a variety of times, then you may get a wide variation in the amount of grip that is being applied to each loaded bullet.

Annealed cases should reset the tensile strength of fired cases back to some sort of unified value. This will result in a more consistent grip on each bullet when using cases of mixed age. But are they any more consistent that un-annealed cases that are kept in batches????

Now velocity variation has already been mentioned but what about barrel time? It is possible for loads to have a similar velocity but still exit the muzzle in different parts of the harmonic cycle and so be off the accuracy node. So by simply looking at your results in terms of velocity when annealing, you are not really seeing the whole picture.

Barrel time covers a lot of things. It is the time taken from the breaking of the trigger sear, first ignition of the primer, powder ignition, bullet release, bullet to barrel land engagement, powder full burn period, bullet travel to muzzle, then finally the bullet exits the muzzle. All these things effect the harmonics of the rifle.

We all know about accuracy and barrel tuning as defined by barrel harmonics. When looking for accuracy, most shooters think of powder charge and seating depth as the things that most effect harmonics. But large differences in case neck tension can too I believe.

From memory, about 12000psi is required before a bullet will be released from its case neck. A tighter grip on the bullet will require higher pressure to release the bullet from its case neck. So if you mix cases with differing cases neck hardness, you will get a large variations in cases neck grip. This will result in variations in barrel time. Bullets will then exit the muzzle at various points in the harmonic cycle. This I believe is the true reason why consistent cases neck tension is so important to top accuracy.

It is a bit like loading a batch of bullet with a large variation in seating depth and expecting them to shoot well. It could happen but we all know that consistent accuracy is best served when the seating depth is consistent and just right. Same goes with bullet grip. Anything that can result in a significant change in the exit time of the bullet must be addressed or you will not get top accuracy.

This may also explain why some rifles seem to have their accuracy go off the boil at times. Maybe as the cases are fired multiple times, the case neck hardens, bullet grip increases and bullet exit time is changes to a bad point in the harmonic cycle.

Bonding of bullets to the neck…… Freshly loaded bullets will have a certain neck grip value on the bullet. Wait an hour and then try to seat the bullet deeper into the case and it will not take much more seating effort than it first did. However wait a month and try and do it. The amount of effort required will have greatly increased due to the bonding effect between the bullet and the cases neck brass. This is why some shooters like to shoot freshly loaded ammo in major competitions, especially if their rifle has a very small accuracy node. Some clever competitors seat their loads long and the bumping them down to their correct seating depth the night before a comp. So breaking the bond and making bullet release pressure lower.

Molly coating bullets also makes bullet release more consistent due to the lubrication effect. It may also reduce the bonding effect between bullet and case neck. Likewise it may even make bullet release more consistent with variations in case age and loads that have been put together months apart. Is this the reason why molly coaters seem to be at the pointy end of F-Open fields at most Queens?