I am trying to load some 235gr Woodleigh Hydrostatics for my 375 Big Bore and would prefer not to encroach on the powder space too much with the long monos if possible. The space between the bolt face and rifling lead contact exceeds 2.8 inches but OAL quoted everywhere appears to be 2.56".

Is the OAL predicated by the lifter and bolt opening or can I risk stretching it, say one-eighth inch, if only for cartridges fed straight into the chamber?

There's no reason you can't seat them longer if you want to load them directly into the chamber.

Thanks Snyper, I will have to do that because the powder won't rattle on the first cartridge I loaded - half a grain lighter than the book starts at - and I didn't even get within 2mm of the 65mm OAL.

I got 200 Hornady 220gr FNs thrown in when I bought the rifle, and they are suddenly looking a lot more attractive.