Nile Swallow was an old friend who helped with corn harvest when I was a young pup. Once, when I was trying to remove some large allen-head bolts that were frozen in place, Nile offered a trick he learned as a mechanic in the Navy back in WWII.
"Smack that Allen-head bolt hard with a hammer a few times," he said. "Don't mar the Allen-head opening, but don't be shy about hitting it. Then put your Allen wrench in and try it again."
By golly, Nile's trick worked. Since then I've refined and possibly improved his technique. I put an Allen-head socket on a breaker bar and try to turn out the frozen bolt with the breaker bar while I smack the head of the breaker bar with a hammer. The impact of the hammer, directed down into the Allen-head bolt while I'm trying to turn out the bolt with the breaker bar, often works magic on frozen bolts.
So I was really pleased to see in a recent tool catalog that some manufacturer has taken Nile's trick one step further. It's a special bit for an air hammer. You install a 3/8-inch drive impact-type socket or Allen-head socket on one end of the bit and put the other end in the air hammer. There's a special hex-shaped segment in the middle of the bit, so you can turn the bit with a wrench while you rattle a stubborn bolt with the air hammer.
It's tough to describe the tool, but it essentially allows you to use an air hammer to do the same thing Nile taught me years ago.
If you're wondering, yes, I've got one ordered. For less than $20, I had to give it a try. If it works, Nile would be proud.