Aww!! come on guys---

300 yds with a quality high powered deer rifle is duck soup with practice from a proper rest!!!

I have shot many times out to 450 yds(150% further!!)in proper conditions with a flat trajectory rifle like a 300 ultramag and hammered game!!
I could take you out with a laser range finder in proper conditions with a Swarovski TDS scope and you would be amazed at how well you shoot!!Leupold has a similar set up with their Boone and Crockett scopes--

No, you should absolutely NOT hold "over hair" and shoot at that distance--you need optical aids and a range finder or all bets are off!!

I would agree that the 375 H&H shouldn't be shoot past 250 yds--the trajectory over sequential 50 yd increments is like a falling rock. You would need to know the exact distance and ballistics to have success on further shots.Personally even with a range finder and optical aids like TDS,I would'nt try it on game.Can you hit with a rainbow trajectory? Of course!! Sharps shooters(45-70,etc)Do it all the time!!

Me?? I want better trajectory to ensure a higher probability of a hit with proper shot placement.That can be done much further than 300 yds with certain cartridges/rifles!!