I'm not sure what to call the space between the bottom of the bullet and the bottom of the shell.

Anyway; there being more or less space where the powder lies in a cartridge has what effect on the performance of the cartridge? Seems to me I heard/read somewhere that less space between the bullet and the bottom of the shell increased chamber pressure. Is that true and what effect does that have on the bullets performance? One would assume it made it go faster but I wonder if it adversely affects accuracy.

I ask this because I load .45 ACP for a Kimber Pistol and went to fire those same cartridges in a Springfield Mil Spec and the action didn’t lock up because the bullets weren’t set deep enough which means that would be a loading characteristic of that gun.

The space is called "case volume", or more properly since the case is actually a part of the chamber once it is in it, "chamber volume". The amount of powder space means nothing as far as pressure or velocity. The amount of powder and type you put in it does the work as long as you leave the volume alone and don`t seat the bullet deeper or shallower, or change brand/shape or wgt.
The likely reason your ammo didn`t fit the Springfield is the chamber throat was shorter and the OAL needed to be adjusted to fit. If you stay with the OAL in the manual for the exact bullet you are useing, provided they didn`t develope the load at SAAMI Max OAL the ammo should fit almost any chamber. There is however no guarranty and a bit of tweeking may still be required.
This is all part of the start low and work up while developing a load that is stated in the manuals. Nothing is cut and dried and what works in one gun is almost sure not to work in all others, whether OAL, max charge, best accuracy, ect.

It was the first time I loaded with the particular bullet that caused the problem. I got a free thousand Hornady, top of the line JHP's with the purchase of their Lock N Load press (not a bad deal). They being shaped like a manned rocket with a capsule (triangular top on top of a straight walled barrel base) when seating them as I did my other bullets (OAL), the transition from angle to straight wall of the base protruded more into the breach. They fit fine in the Kimber but were a good 20 thousandth too long for the Springfield.

I was just curious about variation of case volume since I thought I came across information that that made a difference. Actually the Springfield ended up returned to the gun dealer and will be replaced by a Kimber, so ultimately it won’t make a difference. I'm just a stickler on details; don't mind me.

For the same charge, the deeper you seat a certain bullet, the higher the pressure and velocity will (generally) be. As a rough approximation, each 1% loss in net case capacity produces a rise in pressure upwards of 1.8% (for the same charge). However, seating the same bullet deeper also gives you more bullet jump, and this can affect how much pressure rise you actually get. You can re-adjust the pressure by changing either the type of the powder or the amount of it you use.

That's what I thought I learned of before.

quote:

For the same charge, the deeper you seat a certain bullet, the higher the pressure and velocity will (generally) be. As a rough approximation, each 1% loss in net case capacity produces a rise in pressure upwards of 1.8% (for the same charge). However, seating the same bullet deeper also gives you more bullet jump, and this can affect how much pressure rise you actually get. You can re-adjust the pressure by changing either the type of the powder or the amount of it you use.

That is what I had always heard as well as seen in actual practice.

I'm glad it has become a non issue since I didn’t go through with the Springfield purchase. That's all I need to have to do is have to keep track of which loads are for which gun.