One has to remember that cost containment was often an important desision factor during the period before our government surrendered fiscal restraint in favor of campaign contributions from the military-industrial complex. In 189X, it may have seemed worthwhile to employ a powder that could offer the same performance with 34 grains as another that would take 40 grains. If both were priced the same by weight, the 18% cost difference could be significant.

Of course it's also true that IMR 4350 didn't appear on the market until 1940.

In today's context, it's sometimes worthwhile to compare load efficiency. For example, a 2000fps charge of 4895 under a 220-grain bullet burns about 98% in the 30" Krag barrel while enough 4350 to give the same velocity burns only about 88%. Personally, I don't like throwing unburnt powder out the muzzle if it can be avoided without sacrificing safety, reliability, velocity, accuracy, barrel life, etc.