Locking breach CVAs are few and far between when it comes to having problems with BH 209. I have heard of just as many problems with this powder out of any other gun on the market, yes even T.C.'s. I sell numbers of these guns every week and it all still comes down to the best primer/powder configuration that fits for the firearm.
Where I am from, Minnesota, BH 209 in my opinion is probably the most consistant cold temperature powder out of any gun. As long as you team it with the right primer it will work in anything. We hear nothing but great reviews of this powder. We also hear some negative ones, guess what these negative ones usually don't understand how you have to work with BH 209 to come up with a consistant performer.
Not seating bullets correctly, pure bullet choices, bad optics, wrong primers can all aid in poor accuracy.