There is some problem - or problems when loading .44/40's due to shoulder placement.

I don't thing the .38/40 shares those same shoulder placement problems and might be a better consideration in a historically correct chambering.

The .44-40 has such a short neck area in modern chambers, that proper neck tension is not possible and I suspect alignment with the case and bore might also suffer. Mike Venturino (Handloader or Rifle) write an excellent article on this very aspect of the .44/40 a few month's back. Mike's solution was to shove the shoulder on the cases WAY back to produce a longer neck - I do not agree with that remedy, however, due to the excessive space between the case shoulder and the chamber's shoulder, which promotes case head separations with anything other than REALLY light loads.

Some of the M73 Winchester, makers do chamber the rifle in .45 Colt, while not being historically correct, it would make for much better function without the loading, and brass longevity problems.

I've shot a couple elk with a .45 Colt rifle, a Model 94 Trapper model, many years back. Worked a treat both times! Close proximity and decent shot placement were paramount with the 300gr. Hp's I used.