Any rattlesnake with a once inch bit pattern would easily fit into the two foot range, possibly into the three foot range.

Average adult, insanely common.

So tell that mom of yours to stop it and calm down

thanks piddzorz! =)

thats the answer i was looking for XP

This
Some rattle snakes can get bigger which can mean a wider fang-to-fang width
So in this case size can matter if you want to know how big a snake is in this kind of case.
But like said before smaller is deadlier. No control of venom release.

hope this helps. Pm me anytime with reptile issues.

When you read '66 inches long which is almost 3 feet,' did you think, past that will be, 'the answer I needed?' I hope not.

Its impossible to give you an average poisonous snake that has fangs with 1 inch in between because ''average'' is such a vague word. Do you mean the average snake for your area? The average snake that most likely bites animals when threatened? I did some quick searching to discover that some poisonous snakes that live in Texas that fit your description of fang gap span are: Copperheads, Cottonmouths, and Rattlesnakes. All of which aren't necessarily huge. Probably only 1-3 feet (3 feet being the unlikely maximum).

get a badger or some kind of marten, not a dog