1942 BYF Mixmaster won't shoot!

[DonVoigt]

True on a file, but these ejectors are not always "hard" though maybe they should be.

One can also use a diamond embedded needle file, they come in pretty handy for small spots too.

Polishing after goes without saying, but I should/could have said so!.

Originally Posted by John Sabato

I wouldn't use a file for this, no matter how fine, it will be difficult on such a hard part as the ejector.

A fine grit emery paper on a known flat surface (such as glass or machined steel) will work wonders on polishing the contact surfaces (top and bottom) of the ejector until it moves smoothly in the upper receiver.

Also check the breechblock for burrs in the ejector slot that might inhibit free movement.