I prefer 10 to consider it a "killing" distance.

However, I killed a monster tom ~5 years ago with a single pellet, because the rest of the load went into a 4 inch maple sapling I never saw. I skinnned it out, and it had one pellet at the base of the skull. One other single pellet penetrated the fleshy tail, just enough to puncture the abdominal cavity and refresh my memory as to why birds were termed "fowl"...[:'(] lol

I think between 5-10 (from a 12 gauge or bigger) is a very safe and comfortable estimate. If shooting 6 shot (or higher), I would not recommend shots longer than 40 yards unless you're using a denser load, such as Hevi-shot or Winchester X-tended.

S&R