Hall Sharon's deep groove button barrels of the 70's had rings one end to the other, due to "friction/pressure buildup then relief". They were hard on the eyes to look
through at a light bulb. The .36 I had did shoot quite well with denim patched .375's, though. Those turned into little rounded bottom, flat topped slugs
when seated. They were not difficult loading, with the gun's 5/16" steel rod. The .350's did not shoot well. I assume the slug obturated due to their increased friction,
while the short contact round balls did not obturate.