I placed a wooden dowel in his mouth. He pulled it back on his own to where the bit usually sits and held it there. His lips had 1 wrinkle at the corners of his mouth. I marked both sides of that dowel (his mouth was kind of pushed out at the corners because of the dowel rod but not excessively), but yes.....it measures right at 6". So I'm thinking of looking for a 6 1/2" bit. I just wonder if I should look for a 6" bit instead...????? But I was reading it's best to have a 1/4" space on both sides of his mouth. He just a 15.3 QH. I don't know.....the more I read online the more I second guess my decisions!
I have a 5" bit and tried that.....but it was way too small.