Does anyone know what "beer apples" are properly called?

They're not quite a normal flowering crab. The fruit is about
1.5" by 1" (or a little larger), oblong rather than round, a
distinctive odd shade of red skin, tends to be reddish inside, has a
delightful strong tart flavour, and will make you sick if you eat too
many of them raw but makes the world's most wonderful jelly, and
they have a long and productive bearing season.

The trees are seen occasionally in Montana, but they are rare; have
not seen them elsewhere (I'm now in Calif.) They're big vigorous hardy
trees with heavier branches than most apple trees; I strongly suspect
all the ones I've seen are own-root.

I'd settle for getting some seeds that might be "close enough" to
type, if I can't find the real thing.

~REZ~