I just had a great little story typed out, but I guess I took too long and got kicked off the site before I could post, so I'm not going to type that all out again.
Yes, I have had luck calling out immature bulls, but find that they tend to walk in silently and have had some with initial grunts, and then go quiet, and have had some young bulls come in totally quiet without any grunting.
Moral, is call, call, call, and wait silently watching and waiting. Sometimes your only indication is a branch snap close by. You just never know what is walking in on you, or the size it could be. I've had 7x7 walk in the last bit silently as well, so you never really know the size they are, until you see antlers.
hmmm LOTS of bulls falling with the end of the month AND colder temp...-1 last night at 2am..
5-01..you should do very well 1-14 oct PRIME RUT..remember buck expert moose juice..tampons...and KC CAPLING 22 INCH moose magnum fibreglass calling horn.