Breechplug

I am not really sure whether more or less is the best answer - I believe it is best to have the concave end on the BP. It seems to me it is easier to ignite the tip of the cone of powder and let that burn through the bulk of the powder.

Again the problem that I am trying to help is blow back through the nipple - not ignition. I think if you want to help ignition (if you are having a problem is to install the Lehigh Vent Liner in the bottom of the concave cone of the BP.