I borrowed this pic and info from Ken's bullet list. I thought it was worth discussing.
Ken, I corrected some typos & etc. for better flow of the quote....
Here's something a little different. The first 2 bullets are CS .36 caliber pistol bullets (M97) & the last is a CS Merrill .54 caliber (M67). All are products of the Richmond Arsenal. Notice on the bases of the 3 bullets the punch/centering mark. On all, the punch mark is centered on the solid base...on all the punch mark enters the bullets base at an angle?
Manufacturing error/bullet casting method??
Whatever it is it has happened at least at 3, now 4 times, on two different bullet patterns.
One of those things that makes you say hmmm.These are not punch marks. All of these bullets were cast...base cast. Well, these small holes you see in the pic are air holes...like little funnels.
I've stated in other posts that you should all try your hand at casting bullets to experience and see the wide range of "things" that can happen...and what specifically caused them to happen.
When I started casting bullets, I poured plenty of lead into the mould, which fills up and then pours all over the mould. I said to myself, "that's enough" and stopped. Then I found that it's hard to budge that sprue cutter with the extra lead starting to harden everywhere. After a while, I started counting, to get a feel for when the cavities were just topping off, so I would just have little "caps" of lead atop the sprue cutter. These were much easier to cut off and I'm sure workers, casting with gang moulds, all day long, made their jobs as easy as possible. I noticed that when the cavities were just filled to the top in this manner, as the lead quickly cooled, it contracted and a small air channel formed in the center. This left a sprue that looked like a lead funnel. When the sprue is cut off, the small air hole is left in the bullet.
The pic is a perfect example of what this looks like in base cast bullets. I often see it in nose cast bullets also...making them look like CW magnum rounds.
