Do you think the lower velocity, lower report, lower cost Blue Dot rounds would be effective on the dogs at the ranges we will be shooting?
You probably won't get the "red mist" effect with the lower velocity rounds like you do with the high velocity, highly frangible bullet loads, but you shouldn't have any problem killing them.
The only thing I'd suggest is to make sure you know where the slower loads are at ranges out to three hundred or so yards. Their trajectory isn't going to be as flat as the faster ones.
Myself, I don't see any reason why you shouldn't be able to see bullet impact with any .223 load (At scope powers less than 20X). Unless, like I said, there is a problem with trigger control. At 8 Lbs, I'd say there's an issue with the trigger.
If you feel comfortable with it, and don't want to wait for the factory, download Raynor's instructions and do your own trigger job.