My rifle is a custom Brno 602, and the barrel is a 21 inch Smith with standard for caliber 1:12 twist. The purpose of the .375 Ultra chambering was so that I could duplicate .375 H&H long barrel velocities - which I did with a bit to spare.

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I have loaded bullet weights from 260 gr to 380 andI have found that H-4350 gives me good results across the board. When loading the 260 gr Nosler Ballistic Tip, I reduce the load significantly to reduce bullet blow up, and 2600 fps still shoots flat enough for my purposes.

Barnes 270 gr XLC - 95.0 grs H-4350 - 2800 FPS
Barnes 300 gr X - 90.0 grs H-4350 - 2600 FPS
Barnes 300 gr TSX - 90.0 grs H-4350 not chronographed

Hornady 270 gr Interlok - 95 grs H-4350 - 2800 FPS
Hornady 300 gr FMJ - 90 grs H-4350 - 2600 FPS

Nosler 260 gr. - 90.0 grs H-4350 - 2600 FPS
Nosler 260 gr - 95.0 grs H-4350 - 2900 FPS

PMP 286 gr Mono-Solid - 92.0 grs H-4350 - 2750 FPS

Rhino 380 gr Bonded - 84.0 grs H-4350 - 2300 FPS

Speer 285 gr. AGS - 92 grs H-4350 - 2750 FPS

I rounded off the velocities to the closest 50 FPS, and velocities were measured over a Ohler 35P chronograph at 12'. When I was working up my loads, I would stop when I got high pressure signs and back off 1.0 gr. I often found that by reducing 2.0 grs, pressure would drop significantly, but that velocity would not - therefore most loads are 2.0 grs below what was maximum for my rifle.

PLEASE NOTE - the loads in my rifle EXCEED THE MAXIMUM loads listed in the Hornady Manual!