The best way I have found to even achieve a in focus shot of these plus sand martins, swollows is to prefocus on something, have a high film speed and multiple shots on, use pervious peoples advice then either;
1, Given the relative lightness of the gear your using, you could hold it all while trying to pan along with a bird seen via your viewfinder and wait til its nearly in focus and shot away.
2, Have gear on a tripod aimed at an area you have seen them fly past, prefocus and shot then one comes near.
1 is only for people who like to waste time and shutter counts although if you are patient and stick with it for a few weeks/months with the same birds you may start to see flight patterns/ birds habits which along with ( by this time) a fluid and improved panning action may give you some great results.
2 is for people like me i.e no patients as all you have to do is study your given birds, find patterns, popular flight paths, find locations parhaps where their flight path is limited as shown by my photos below where I daw some fly down paths or a stream.
With these small fast birds using the auto focus is not a good idea, most ( me included) will manage to focus on them in the sky but in most cases all you get is a dark ouline. To compensate for this you try with some background, trees, field, but in most cases again all you have is nice trees and a bird in differing degrees of out of focus.
If your starting this try 2 first, I have per shutter counts achieved more success with 2 then 1. If you do want to achieve a great photo with 1 then your in for some serious devotion time with your subject and if nothing else your get stronger arms.