DGA stands for 'dam* good action' .. and they are. A 22" bbl may have been set back one thread & cut as the std. bbl length was 24". You could contact Shillen & see if they have a record of the gun's original configuration.
Also, it is a good idea to be sure it will chamber & feed a factory round loaded with the heaviest [longest] bullet you wish to shoot. There is a slight chance it has a 'tight neck' or even a 'no neck' chamber &/or a short throat and if it does you want to know that before buying it.
