Ron,
I think you put a 5/32 flame channel in your plugs right? I want 5/32 flame in my plug for sure. No exceptions!!
Yes, the flame channel will be 5/32", and it will come back with one of your flat head vent liner installed, and it will reliably ignite Blackhorn powder. Or would you rather have one of my vent liner?
Now just to be sure, you are sending the plug out of the rifle right? not the Blackhorn QRBP...... The Blackhorn QRBP could have the flame channel drilled out to 5/32", but i wouldn't want to install a vent liner in it.