Gentlemen,

my comment on this topic because I had this question also...

I have a Sako in .375 H&H which had a 61cm barrel (ca. 24").
For I am not a big person the handling of the rifle was not feeling "right" for me.

I ordered the barrel to be shortened to 56cm (ca. 22"), and now the rifle handling has much improved (muzzle diameter is about 17,5mm / .69").

I use medium burning powders (i.e. Kemira N140) for the .375 H&H, so the energy loss and the muzzle flash are also ok (Hornady 270grs SP, Sierra 250grs and 300grs SP).
If you intend to use slow powders (like Reloader 19) for the .375 H&H, I would recommend you stick with the original barrel length.

best regards
Rolf