After fireforming 50 cases this past Sunday, I checked the capacity increase from cases of the same lot. Notes are at home, but the average gain in case capacity (weighing cass water filled to the base of the neck) was about 2 grains of water, or a whopping 3.8% capacity increase.
Using the 1 in 4 rule, that should allow about a 1% increase in velocity. Figuring around 3000-3050 with 100 grain bullets for the parent, that gives us 3030 to 3080 fps. Obviously not something to write home via Priority Mail about.
Funny that the 260 gains a hair over 10% in capacity when AI'n verified pretty thoroughly here.
http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/4686301/all/260_Rem_or_AI
