Yes, you can use heavier 38 bullets. In reality, you can use heavier 357 bullets, but you must be sure to crimp them more, and make sure they will not bind the cylinder by being too long to start with. I remember shooting a number of 158 loadings, that worked fine, and quite a few more that did not in the 125gr. Marked sp101 I had.
With the shorter cylinder, the problem is not pressure, rather the remaining bullets in the cylinder unseating ever so slighly, thus becoming slightly more elongated in overall length, during recoil - which then binds the cylinder due to bullet projecting beyond cylinder.
This problem is definitely noticeable with the scandium frames. Even with longer cylinders, you must be careful to be sure ammo is not in the cylinder for too many firings. Example, if you fire four of five 357 rounds, then reload only the four fired, fire those same four chambers, reload again, you may wind up binding the cylinder with that one chamber containing the bullet that has endured so many rounds being fired. The overall bullet length will definitely be noticeably longer.
