Sprite positioning on the 2600 is a lot weirder than you'd expect.  For some reason my missiles were always off by a pixel.

I hacked in some missile offset code to compensate and make things look good.

The sprite positioning code in my book and other online sources all pretty much had the same issue.  Then I found this:

https://bumbershootsoft.wordpress.com/2018/08/30/an-arbitrary-sprite-positioning-routine-for-the-atari-2600/

When I put in this sprite positioning code I had to undo my hack to make things look right.