Things to remember on reamer design:
A. neck clearance, take into account the skim cut on the neck if you want to clean it up. You want a minimum of .004 clearance in the neck of a loaded round.
B. .240 Freebore is very, very long. There is also another .015 at least that comes off the case mouth on that 45* angle you see. I would not go longer than .190. Stuff the bullet down in the case, and monitor for doughnuts.
C. you say you have .030 Cartridge base to ogive on a new barrel, Length of the cartridge for magazine use. Few hundred rounds and your have zero clearance in your mag box...plan for success, give yourself more clearance. Planning on .030 clearance on a new barrel, is in deed planned failure.
D. .514 dia in front of the Web. Get samples of the brass you plan on using and mic it with a good micrometer, not calipers. Give yourself .003 at a bare minimum, and you may want to buy the set of dies you are planning to use in advance, size some fired brass, and see what dimension the dies size to taking into account the spring back.
E. I like #5 contour barrels, and Brux is at the top of my list. If I were hiking in the Utah mountains, I would either have the #5 fluted or go #4 contour. The less machining on my barrel, the better I like it, chambering and threading the muzzle is all I will tolerate. I expect a custom hunting barrel to shoot at least in the very low 3's, preferably better. 1/2 MOA is border line for me, 1/4-1/3 MOA is acceptable to an old benchrest shooter/hunter, and 5/8 MOA is time to set a barrel back or put on a new tube.
F. 7 Mags have some recoil, you need some weight for controlling recoil.
G. Alex Wheeler on accurateshooter is a darn smart cookie when it comes to building long range deer and elk rifles. He knows his way around long range rifles, and will steer a guy in the right direction, first time!
H. Magazine box OAL will eventually have something to do with your barrel life, so change your expectations, and plan on eventually shooting a single shot.
I. if you want to use the magazine box for all hunting applications, then plan on 600 and MAYBE 800 rounds of useful barrel life. This short barrel life, does not leave much room for load development, thus the shorter freebore becomes more attractive.
In the past, I have gone much tighter dimensions than the ones above, and experience has a $ cost to the learning curve. For instance, .002 clearance on the .514 web dimension...really bad thinking as this was what Target shooters use. I did not check the dimension against the web of the brass nor the dimensions that the brass was sized to. I had to have RCBS make me a small base sizer, and RCBS does not offer this service anymore. Often, the most accurate load that is shooting 1/4 MOA is on the ragged edge of high pressure, plan on success giving yourself some breathing room in the web.
ON a more positive side, I have gone .110 FB using 168g Bergers with no problems, Remington & Win brass, R#22 and R#26, and Retumbo at 3100 in a 26" and one 28" that was 3200.
Two things, I don't like the cost of a carbon fiber barrel, and I do not like the way a reamer pilot rides the tops of the lands of 7mm 5 R rifling. If/when the reamer pilot falls down in the trough between the land tops, this creates reamer chatter. There are ways to "hide" & clean up chatter. Tight fitting reamer pilots can stop this problem, but they also may cause other problems. Many gunsmiths will not chamber a 5 R barrel for this reason....many. This 5R issue is controversial I know, but I don't take a chance. Give me a good 4 or 6 groove barrel any day, personal preference.
Shoot for accuracy in the extreme, don't cut corners, and GRAND success is sure to follow.
