A little while ago I was asked to put a 375 H&H load through Quickload to see what the predicted velocity and pressure was, this load was 2 grains under max from the Barnes number 4 manual (1st printing) using a 270 Grain TSX.
The powder in question was Winchester 748. The results predicted a velocity of around 2600 fps, but more frighteningly (is that a word?) a pressure of 89 000 psi.
Fatboy404 and I put our collective heads together and had a think about this, after looking up all the other Barnes manuals it was noted that the number 4 manual is the first one they used 748 in the 375 H&H, all the others use Win 760 (along with all the usual powders).
I e-mailed Barnes to ask the question, thinking maybe a typo, should have been 760 instead of 748.
Below is the actual reply I received from Barnes.

David

We pulled the Win. 748 data after the second printing of the number four manual, because as you noticed it was giving too much pressure. Please disregard any data that uses Win. 748 in the 375 H&H Magnum.

Thanks,

Ryan Farr | Consumer Services
Barnes Bullets, LLC

38 North Frontage Road, PO Box 620, Mona, UT 84645
Phone 435-856-1000 | Fax 435-856-1040 | ryanf@barnesbullets.com
Freedom Group Family of Companies: Remington | Marlin | Bushmaster Firearms | DPMS / Panther Arms | H&R | Barnes Bullets | Advanced Armament Corp | Mountain Khakis | EOTAC | Dakota Arms | Parker Gun

I'm posting this here, not to give Barnes a hard time, but just to alert any other fellow shooter around the world to the mistake and please DO NOT use Winchester 748 load data from the 1st printing of the Barnes #4 manual.

Regards,
David.