Depending on how long ago he swapped It's going to take him a while...A4S is pretty tricky for machinists and if he's new to the job and new to doing it on a4s at the same time his dps will be crap (and he's only i198 which is kinda low). So that looks about right for someone just picking it up.

Also you should post some more information if you want more information...821 DPS means nothing really...If he's 821 at the start it's super bad, 821 after he's had to sac himself and still doing 821 isn't to bad though since he's a noob. Also shouldn't he be here asking for tips or looking at this and not you? :P.