HandyAndy, From what I can tell the angle tip works only on a full sleeve tube caulk gun like the one I indicated above. They will not work on a open framed caulk gun as the tip needs to be secured against the end of the cartridge in the caulk gun or you just get a huge mess squeezing out the side. You can order one of the caulk guns
HERE (least expensive I could find).
On the 45 degree tips, you can order them through Lowe's on-line for ship to your home or in-store delivery at the Lowe's in Corralville, IA (seems to be nearest location to your Iowa City locale). The Lowe's website says they can be delivered to your home by Monday Sep 23rd or pickup in-store in Corralville Wed Sep 25th.