Owl calls require some back pressure to work correctly. Back pressure is created by restricting the air flow at the end of the call. The exhaust it is called.
There are several ways to do this. You can turn the exhaust end on a stepped mandral, either one you buy or one you make. A stepped mandral will have one end that is small, say 1/4" and one end that is large, say 1/2". These are easy to make with a standard pen mandral and some spacers. You then need to drill the blank you are going to use for the exhaust first with a 1/2" hole part way through, and then the rest of the way with 1/4".
Or, you can drill the exhaust end a straight 1/2" and turn it. Then when you are putting the call together, to get the back pressure, you can take a piece of wood, drill a hole in it 1/4 inch, and then turn it to 1/2 inch and glue it in the end of the exhaust to create the back pressure. You then sand or ream that hole to tune the call the way you want it to sound.
The rest of the call is exactly the same as putting together a grunt call.
Remember, we are talking about game calls here, and being call makers. If you think you are going to buy a kit, ANY kit, stick it in a hole and have a great sounding call, you will be disapointed. You still need to experiment a little to see what length barrel will work best for you, what lenght exhaust, what material you want to turn the call out of, and a lot of other factors.
One of the best pieces of advice ever given concerning call making comes from Dogcatcher. He says, get a note book and write everything down, so you know what you did and what it caused. Then when you have questions, come back here and we can offer you suggestions.
It sounds a lot harder than it really is. But making these calls is fun and you can make some great calls with the kits. With any kit, from anyone for the most part. It just take a little patience and experience and you will be all set.
Shout if you need ANY help at all. Lots of guys here have been in the same boat you are right now. I can assure you, I was.
E mail me if you get stuck or want to know something else, or post it here if you want. No one is going to whoop on you for asking a question. You have my word on that
Al @ THO