38" and 42" - only 4" difference. With a different contour in each, they could feel identical in weight and balance - therefore the 38" would handle both the target aspect of having nice steady hold, and shorter length, being better handling in the bush.
I've hunted in bush where a 32" barrel was too long to swing onto a deer or moose, and in other "bush" where a 42" was just fine - it varies from bush to bush and even inside the same block of bush. I would not pick a barrel length between those two 'long' lengths on 'just' that criteria, but would let design decide for me.
An "Edwin Marshal' rifle with 38" is one of the best hunting designs there is and it is so balanced as to be a great 'target' shooter too. This is the rifle Gary Mummery shoots every year at Helfely Creek and it is a "winner".
I think it's a "C" weight in .50 @ 38" would be perfect for both theaters, IMHO. It is also perfect in 42", as attested to Taylor's Virginia rifle - at around 10 pounds, it's perfect for those who like a bit of weight - but perhpas not the 'choice' for everyone. This is another of those 'subjective' deals.
For a 6'2", 210 pound fellow like Taylor (or 6'1" @ 230 - like me
), 10 pounds is perfect - easy to shoot and nice to hold.