Smokeless powder responds dramatically to backpressure.
Amazing as it may seem, a 50 grain 5744 charge with a 40 / 50 240 grain yielded 2118 fps. That IDENTICAL weighed 50 grain charge resulted in 2082 fps with a 100 grain heavier bullet, the 340 grain 45 / 50 Dead Center. A whopping loss of only 36 fps for a bullet 100 grains heavier, with virtually identical trajectory. The massive increase in energy is on the chart above.
The most vivid difference is the totally different sabot material and thickness in the 40 / 50 vs. the 45 / 50, as well as the bullet weight. So, yes, it is possible to get actually slightly higher velocities with a heavier bullet with roughly equivalent powder charges of 5744-- with a sabot change.