I have a 1979 production 38-55 with a 24" barrel. [Legendary Frontiersman] I really like this rifle a lot.
With it I shot my largest Whitetail buck, and it is quite accurate with Jacketed and cast. I can drive a 255 grain Barnes jacketed to over 1800 with ease.
The 285 grain GC cast bullet will make 1650. These are very effective loads on game out to about 200 yards.
However, factory 38-55 loads are quite "soft" The Winchester 255 grain offerings I chronographed at a leisurely 1250 fps. [Older CIL ammo was closer to 1600]
I put a Williams firesight on front, and the venerable Foolproof aperture on the rear. If I do my part, it will shoot both those bullets into 1¼ moa, plenty good enough.
The 375 will mirror those results, and I can only think that if I had a 375 instead of the 38-55, I would be just as pleased.
One point worth noting is that the 375 has a true .375 groove diameter, whereas the 38-55 varies considerably. [I have slugged these and seen from .3765" right up to .379"[ Mine is .3768"]
My 38-55 does not particularly like the Hornady 220 grain .375" pill, but shoots the 255 grain .375 Barnes designed for the 375 Winchester just fine. I still prefer the 255 Barnes that is listed for the 38-55 at .377" diameter.
Regards, Dave.