7 RUM, coal & freebore with 195 Bergers

[hemiford]

I'm researching for a new 7 RUM build. 195gr Berger, LONG barrel build.
If I seat the Berger with the boattail/bearing junction right at the base of the neck of the case,
by my arithmetic I end up with a COAL of 3.961, which fills up about .361 of the .400 freebore,
leaving the bullet only about .040 off the lands. This leaves roughly 103 grains worth of empty
space in the case for powder, using the 195.
This situation smells funny to me, I suspect this loading scenario is unworkable, and I'm not even picking a powder yet.
To those who like speed out of the 7 RUM, how are you setting up your bullet length and freebore ?
Are you reaming out the throat to maintain .400" freebore ?
If you bring the freebore back out to .400, you end up with about .150" bullet jump. I don't like that either,
but would rather play it safe controlling a pressure spike.
I don't have a target muzzle velocity in mind, just "as much as safely possible". So at the moment I'm
juggling powder load, freebore, and bullet jump (in my head and on paper).
I should mention, I will likely single feed these rounds so mag length considerations do not apply.
I think the 7 RUM club is kind of small, I hope posting here is the correct forum here on LRH.
Thanks much for any advice (except Don't Do It) !

 

[Lefty7mmstw]

I wouldn't go short freebore on a 7rum. I have one built for around a 3.8" cartridge length with 175 eld-x pills seated to 3.670". I'm running powder charges more akin to a 7mmstw than a 7rum. 86 h50bmg with the 175 eld-x produces 2900 fps from the rifle. I suppose I could push faster, but I've already blown a couple cases with book loads with powders like rl25 and retumbo. I went with h50bmg to get the load density up to a usable level as the reduced charges with some of the faster magnum powders would have fallen below 80%. That's a bit low for consistency in this case size.