You sanded down the web area and the case chambered... so here's the issue:
You're not getting enough sizing on the case.
Check OAL of these cases also. I'll bet they're longer than 3.715", which is the Lapua factory length. I've found some of the Hornady cases I've shot come out of the chamber at 3.740" !! WAY over length.
And I'll bet you something else... you cannot slip a bullet into the neck of the fired Hornady case, its neck is so thick and the Savage chamber so tight that the neck isn't releasing the bullet until pressures darn near spike. (You're sanding the wrong end of the case, perhaps!)
On the sizing issue...
Just because you screw the die into the press until it touches the shell holder, that does not mean you're getting enough sizing on the case. While it is true that a fired case should re-chamber easily enough,
if they're being shot over-pressure (for the reasons I mentioned earlier), they'll stretch too much and need a FULL resizing... here's how to make sure you're getting it done:
You want to turn your sizing die in about 1/8 turn, in increments, FARTHER than the shell holder will allow with no case in the die. Then try to chamber the case... if it resists chambering, turn in another 1/8 turn and repeat. The press must still cam over each time, of course...
You see, when the die goes into the case, that puts the press under a load and you'll see that even though the ram goes all the way up, there is a sliver... a tiny gap between the die base and the shell holder. This happens because once the press gets under a load (from inserting the case into the die), the linkage "springs" a bit, and doesn't bring the ram up as far as it does with no case in the die.
So turn the die in a bit farther than you think you need to. That'll cause the case to be sized at the web area, which is what you're missing.
Trim the Hornady cases to 3.715"... turn the necks a bit, or at least take off half a thousandth or so off the outside of the case neck, so that it can relax enough the release the bullet (do this only if you find that a bullet won't slip into the case mouth of a fired case)...
Then relegate the Hornady cases to lighter pressure duty, maybe looking for 2500 fps from 300 grain bullets... or 2600 from 250's... that should make them last quite a bit longer.
If you want to put the pedal to the metal... get some Lapua brass.
Please write back in response so we'll know how this issue is going...