I have had 3-4 7mm Remington Mags and really love the original concept and original ballistics (3260 with a 150 and 175 at 3020) but have a hard time loving the actual cartridge.
Today, the cartridge struggles to get anywhere near original ballistics. Mine have all been finicky, though some have been accurate with certain loads. What I haven't achieved with the big 7 is accuracy, velocity and lack of pressure with a given load. In fact, I have struggled to get much more than hot .280 or .280 AI velocity without pressure signs.
I have read in multiple places that the combination of a shorter neck and just the right shoulder angle lead to quick throat erosion, which causes some of the problems with the cartridges. My assumption is that this is what makes the cartridge in my words "finicky."
I can't seem to find an AI version of the cartridge on any reamer list so am thinking of designing a wildcat, unless something similar exists. My goals are as follows:
1. Stable, accurate cartridge that is not subject to odd pressure excursions.
2. Targeted ballistics of 3000 with a 175, 3100 with a 160 and 3200 with a 150 with below 64,000 PSI MAP (not having a ballistic lab, this may be hard to determine).
3. Ability to use 7mm Remington Mag ammo with no adverse consequences to gun or brass (other than fire forming).
I am thinking starting with a 7mm Rem case and:
1. increasing shoulder angle to 35-40 degrees
2. possible decreasing body taper, but maybe not
3. increasing leade to closer to tight Weatherby type freebore, Maybe .250" freebore of just over bullet diameter.
The 7mm Weatherby acheives all my goals other than number three so maybe that would be cheaper. Not sure what custom reamers and dies cost.
For those, who have created or messed with wildcats, what are your thoughts on the above?
