I had a partial case head separation using a 1.8oz buffer

[BluntForceTrauma]

BluntForceTrauma forgive my ignorance, but how does one know the type of feed cone they have for their barrel? How does one know if their barrel has a cone that goes deeper into the chamber than another barrel's cone?

To me, this area, while the round is in battery, is clearly where the case is unsupported. And theory says that the bigger this exposed area, the higher the chance of it promoting a failure under high pressure. All other things equal.

Reference the photo of the cutaway 5.56 chamber in Page 3, Post #51. A 5.56 chamber first has a 120° cone, or ramp, cut into the breech leading into the chamber, and then the edges are radiused .0625. So, when visually examining the breech, you'll see the flat surface of the breech and then a relatively wide "circle" — that represents the angled cone and the radius — around the chamber mouth. The smaller that "circle" around the chamber mouth — representing a smaller angle and radius — the more supported the case web area.

Attached is a completely random and unrelated photo — I don't know what cartridges these barrels are chambering; I got the photo by Googling "AR15 feed ramps" — but the photo gives a rough side-by-side comparison of the visual differences of different "cone" sizes. The cone on the right, for example, is smaller than the left.