Here in South Carolina, buckshot is still used on deer drives. One club I was in had deer drives. I have both killed deer (a big one is 130 field dressed) and cleaned a bunch that were shot with buckshot.
Here are my conclusions.
The size of the shot needs to be # 1 or larger. ( #1, 00 or 000)
Check your pattern. When the specific load will not stay in a 12 inch by 12 inch group, you have hit your maximum range. Test each load.
Check your point of impact. A plain bead sight can work, but it's difficult. The inclination is to raise your head off the stock and throw your shot high. I strongly suggest some sort of rear sight - the inexpensive clamp ons work OK.
Do not believe what others say. Test your gun, your loads and determine what works. I have had some unpleasant encounters with folks who have the most outrageous ideas about buckshot.
Try to remember that your really shooting the deer with a small number of .32 pistol bullets flying in a slightly diverging formation.