Are you talking about faced bats with the flange? I read this stuff and have no idea, yet I was in construction for 50 years.
Insulators use a hammer stapler. Yes, short legs work best on old seasoned wood. For the channels you might want more accuracy than a HS will offer. If it's worth it to you (and things like this are cheaper now) get a powered one. Electric or air, doesn't matter. You might not like holding a cordless battery one up all day. But a manual one will wear your hand out. You can injure your hand if you go too long. But they are cheap and accurate.
The funny thing about hammer staplers is that you will go through a lot more staples. People go crazy with them — they are fun. And you will miss a lot until you get good. If you get one, don't go cheap, they jam a lot. IDK if you need a Milwaukee, but.....
