A freebore type powder charge is one that has been lab tested as a max charge for a regular Weatherby chamber with freebore.
Run one of those, or factory ammo for that matter, in a zero freebore chamber and it isn't surprising that velocities are high. The laws of physics not being dependent on a particular chamber reamer, it's a pretty good bet that pressures are higher too.
You missed the point. I don't know what the actual powder charge would be with my lot of powder in this barrel with this brass, this primer, if it had a sloppy SAAMI chamber with freebore. You don't either. All that matters is what works in this gun.
Factory ammunition won't come near chambering in these guns......the neck is short for use with 7Mag brass. Wby cases have a very long neck and are trimmed .050" to fit. A 100gr bullet just off the lands seats to where the neck/shoulder radius begins.
