This is typical to the training dummy. This is why when you suspect something is a combo to be sure to test it in every possible way to ensure that it is 100% guaranteed.
With that said, it all depends on how my opponent reacts. Lots of factors can come into play to make them want to tech. If you have them caught in multiple mixup options that they keep getting hit by, during this time they would be more likely to tech so doing WR B after connection BS 1A isn't a bad idea. You could also do BS 66A as a tech trap as well, which will catch certain side techs. However, if you're looking for 100% guaranteed damage, then BS 2K is the only option they can't avoid.