The ammo was all from the same box. It might be interesting to see how another lot does but the velocity I'm seeing at normal temperature is consistent with Speer's published figures and independent tests. I believe it's unlikely that this is a bad lot.
It's not the velocity that I think may be the problem, but the bullets themselves. As Mike Irwin pointed out, the short barrel Gold Dots' velocity window includes velocities well below what you were getting. They do this because different guns can shoot fast or slow, so the bullets need to perform at a range of velocities to compensate. What I'm wondering is if perhaps the jacket or core was harder than it's supposed to be and thus produced the lack of expansion at low velocities. The issue is that even at the reduced velocities you recorded from a cold gun, those particular bullets should
have still expanded.
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