Ahh the barrel length question. My 416 Rigby a CZ550 has a 25inch barrel and a 15" length of pull and is too long overall in thick tight scrub. Take a couple of inches off overall length and it would not be to bad.

For a 375 H&H I would not go below 22". I had a bloke on a bench next to me with a 375 H&H with an 18" barrel. It was horrendous. When he shot it showed a reading on my Chrony. Unburnt powder a lot of which was spewed onto my bench. I would think with the amount of unburnt powder on my bench after each shot even a 20" barrel will produce unburnt powder.