Thread: Relationship Between Case Capacity and Muzzle Velocity

Greetings All,
To ZQLewis. I was aware that the 99 had been upgraded for the 08 group of cartridges but the action is still not the equal in strength of a modern front locking bolt action. If I had a 99, which I regrettably do not, I would likely work up to approaching factory ballistics for decent case life and trouble free operation.

To Nor-west. Firing an original load in an AI chamber produces much less velocity and also less pressure. The relationship between charge and velocity in the same chamber is quite linear. If you graph charge and velocity for a single cartridge and projectile weight it produces a straight line. A slightly larger case will produce a line that is parallel to the first but at lower velocity. Much of the extra charge in an improved case just gets you back to where you started. All sorts of wonderful things were promised from the AI case shoulder most of which have been proven to be myths. I don't think that there is any reduction in bolt thrust as the case just stretches between the head and the body and this is determined by the brass strength and thickness at this point.

To Caberslash. Yes brass quality will have an effect but the same pressure will still be there and the stress on the action will be the same. I prefer to keep substantial safety margins and only go past published data where pressures are known to be low as with much of the data for the 6.5 x 55.
Regards Grandpamac.