Yep, factory 35 Rem. loads are probably kept fairly tepid in deference to all of the old Rem. M14/M141 pumps still in existence. They supposedly follow the same practice with 8x57 loads and several others, for the same reasons: Old guns that might not withstand pressures that modern guns will.
I still shoot Rem. 200gr Core-Lokt factory loads in my M336 for these reasons: They were inexpensive, are very accurate and thus far have flattened a few deer with no fuss. When they're gone, I'll use that empty brass to whomp up a load that has a tad more oomph, providing they're just as accurate as the factory loads were.
The 35 Rem. is not a varmint or target rifle that gets fired hundreds of times per year, so ammo quantity demands ain't all that great. Doubt mine gets fired more than a half dozen times per year, but when I need more ammo, it'll be my own loads.
I have few reservations about loading stout loads in the Marlin 336 because I did it for years in my 444 without any problems. Although like someone pointed out, the hottest loads are not always the most accurate ones and accuracy is still the final answer in my book.
