rduckwor -
I no longer have any, so I can't confirm this without buying another, but I believe the large diameter portion is definitely less than a 24" rifle barrel length. If the small pull cord breaks at the connection point, you have a problem.
I've read about Project Boresnake, and I think it's an excellent idea. I doubt there are very many M16's or M4's with long barrels, so there may not be a problem with shorter barrels. Or, as you said, pistols.
I have varmint rifles, and for me, it just wasn't worth the risk. I think I held one alongside my barrel and said, "Yep. That could be a problem." That was a couple of years ago, so I'm not sure.
Apologies if I'm wrong. No intent to bash a product with value, just to point out a potential problem area.