The 338 Lapua is longer than anything I would be reloading, COAL = 3.681" Wouldn't be able to load a 470 NE, but that isn't an issue for me, but is something to consider. The RCBS Rock Chucker Supreme lists a ram stroke length of 4", which I guess suggests it can handle cartridges with a COAL of 4".
From another source of info:
I load for 338-416 Rigby Improved, 416 Rigby, 500 NE 3 1/4” and 505 Gibbs on a RockChucker Supreme press. The latter 2 cartridges have 1” die bodies and the large opening is very adequate for all cartridges listed. Even the huge 505 Gibbs has heaps of room to place a bullet atop the case mouth prior to seating it. I had a Redding Big Boss II and an RCBS Ammomaster, both had handles that were too long and cumbersome, giving me back problems using them. Sitting too far away from the press was the problem.
The original RockChucker is rather limited in the opening size for the Lapua, even loading 375H&H on mine was a chore. I got plenty of pinched fingers loading that case on my original RockChucker.