You can do kind of a 3D mental excecise every time you look at an animal from a frontal angle. Study a good anatomical drawing of the vitals of an animal broadside, then mentally rotate the animal around slowly until the view is front on. Not very complicated really. The hard part and tricky part is getting the bullet there- ideally at the junction of the heart-lung area... specifically the top edge of the heart from those variable frontal angles.
Think about how and why most animals we hunt are built the way they are... for some kind of frontal protection... from broken limbs and staubs they run through to getting jabbed by others with horns and antlers. Cape buffalo for example have a very tough, overlapping design built into the arrangement of their ribs that is protective from frontal assault. Add to that overlapping design, heavy neck muscles and heavy shoulders and leg bones and the barrier to that best vital zone is substantial. To reliably get a bullet into that heart-lung area from the front, calls on more precision in bullet placement and better bullet construction and the larger the animal the more massive the bullet needs to be for momentum for the needed penetration. Bullets are getting better but the lack of supply of the best premium bullets, especially during this worldwide supply crunch of components, requires diligence and sometimes more $ in getting and using the best available. Frontal shots are inherently tricky because of the increase in the potential for superficial wounding and bullet deflection.
