I have half a dozen or so of these kinds of locks and never once have I found anything in them holes. I take that back, I did find some power graphite in a schlage today, but that is it. They must you the same plug on const. and non const. locks, then charge more to throw the BB in there.
yeah they use the same plug for both setups (normal, and const.) of cylinders, i assume a locksmith could "construction key" a lock for you if you asked or whatever, given the plug is drilled with the extra holes. i suppose its cheaper to just make a trillion of the same plug rather then make 1.4 billion of one plug and 100 million of another. (i think my math might be off)... at any rate even American padlocks often use a 6 pin cylinder in their locks, and only pin the lock with 5 pins, that way they only have one cylinder design.