Played on BizHawk 2.7 with the Gambatte core.

Broke my own WR by another 18 seconds!

I discovered that making a swap just as the last row finishes spawning lets it spawn without triggering the game over, yielding an extra 6 blocks of ammunition. Problem is, if you make the swap just a split-second late, it's an instant game over, so this torpedoed my run completion rate. But after many hours and over 1,000 attempts (most of which ended in a game over in about 8 seconds), it finally paid off.