LK vs BK breech plugs

[gdKelly3]

I have both a LK and a BK rifle. I converted the LK over to 209 but left the BK using #11 primer. Had both down cleaning them and noticed that one #11 breech plug had threads all the way to the end and the other #11 breech plug did not have threads down to the end. For the life of me I cannot remember which one I took out of my BK. Does it matter which breech plug I use in the BK? The one with that is threaded all the way to the end seems to screw a little further into the breech. Also, when I convert the BK over to 209 breech I've noticed that none of the conversions have threads all the way to the end. Does this matter?

Gerald K.