Tom, sent you a PM. I have done some research with my gunsmith and sent you ideas.

My suggestion is first buy the gun of choice. See how bad or good the chamber is from the get go. Pick out the most probable bullet you will shoot. Lets say, a 165gr bullistic tip. See what the furthest out you can load and still fit in the mag. Should be around 2.85". I suggest then loading some dumby shells to 2.8", (max SAAMI specs) Take your fireformed brass and bullet combo to a gunsmith, and tell him you want be able to touch the lands with this combo. That way, with 2.8" you can shoot most if not all factory ammo, but now you have the space in your mag to customize.

Lots of good articles about COL. Seems guns generally has 2 sweetspots, and not always right to the lands.