I just received the latest edition of Guns Magazine. As usual, Mike "Duke" Venturino authored a couple of articles. One, which is titled, Confessions of a Cast Bullet Nerd! includes several references to bullet "obduration", which had me initially
and wondering if I've been spelling it incorrectly for years. So I quickly pulled up Wikipedia, my favorite on-line encyclopedia. Sur' 'nuf the correct spelling is obturation. You'd think the "Duke" would have this straight by now.
Here's some of what Wikipedia had to say:
Obturate means to block or obstruct.
In conventional English usage, obturation refers specifically to the condition of being obstructed or occluded or the action of blocking, stopping, or filling something up. The mechanism by which an undersized soft metal projectile enlarges to fill the barrel is, for hollow-base bullets, due to expansion from gas pressure within the base cavity and, for solid-base bullets, upsetting - the combined shortening and thickening that occurs when a malleable metal object (e.g. a rivet) is struck forcibly at one end.
Wayne