BigBob

charliebrown,
There is another little problem that raises its ugly head when you start converting larger cases to smaller ones. I'll use my 7mm-08 as an example. S.A.A.M.I. specs for case length of the 7mm-08 is 2.035" and in trimming cases the "smart ones" instruct reloaders to trim .010" shorter than S.A.A.M.I., or to 2.025". I was able to determine that the length of my chamber was actually 2.057". Had I trimmed to the length suggested I would have had three results that I didnot want.
1) The bullets would have had to make a jump of .032" to the lands.
2) I would have been unable to seat the bullet out far enough to almost tough tue lands.
3) With factory 7mm-08 cases the necks would have been thin enough to over work the brass during firing and resizeing.
I corrected the situation by converting .30-06 cases to 7mm-08. In doing so I could make the cases as long as I wanted to. They ended up 2.050". Now I could seat the bullet out long enough to reach the lands. That took care of two out of the three problems. At this point I had some nice looking cases, however they were useless. What was now the necks of these cases had been part of the body of the cases, and the necks were to thick to permit the cases to chamber.By turning the necks to a thickness of .016" the diameter of the necks, with a bullet seated, was 2/1000 smaller than the the diameter of the chamber neck. this allowed the necks to strech enough to release the bullet during fireing without increaseing pressures. By useing a Redding competition neck sizeing die I could size the neck of the cases to the exact size I wanted. Turning the necks is the step that is often overlooked. However turning the necks is important. If it's not done there will be an abrupt increase in pressures IF the ammo will even chamber. It's a lot more work, but I think it is well worth it. Right now I'm working on a new .30-06. I'm getting ready for an Oryx hunt next month, and the .30-06 will be my backup rifle should my 7mm Rem. Mag. get dropped or something. Here again, the Chamber is longer than S.A.A.M.I. specs. To get the case length I want I've had to convert .270 Win. cases to .30-06. When a case truely fits a chamber, to accuracy gets pretty good. I decided on the load today. The O.A.L.=3.428". the load is 59.5 grains of H-4350, CCI BR-2 primers and the Sierra 165 grain spitzer boattail bullet. Average velocity for ten shots=2832 fps, ES=11.0 fps, SD=5.1 fps. Five shots, off a benchrest=.247" center to center. I'M HAPPY!!!!!!!!!!!!!!
Converting cases to your rifle is a lot of work, but it does pay off. I hope that this is of some help. Good luck.