I gave this a look, made it through the first 20.
I have to say that I'm not your ideal audience, I'm not a fan of westerns at all, so that really didn't help.
I'll give some notes on some things I noticed though.
I'm not a fan of an unorthodox title page, just keep it simple.
I feel like there is some over writing.
Note sure I have ever seen this before:
The pouch is an Apache amulet to protect against evil
and is worn around the neck.
The note with a border around it? If a script is meant to be visual how will the reader know visually what this is?
This was confusing:
There's never been anything so
terrible. Never. This is worse than
wars. Worse than...I don't know.
Hey, now, don't get all preachy on
me...I just wanted to hear an
amusing little story while I wait
out the storm...if you're going to
start preaching, I think I'd rather
go sit and listen to the rain.
The Preacher only said 4 lines, it wasn't preachy at all.
Your O/S should be V/O's when you go back into the past. Off screen implies exactly what it says, that the person talking is in the scene but not on screen. This would be a voice over.
I still have no idea what this woman looks like:
Followed by the Captain is a beautiful WOMAN (late 20's).
Heavenly and angelic.
Heavenly and angelic? So what does she look like?
This may very well turn into a great script but I wasn't hooked by page 20 and that's a problem, again though, I don't like westerns.
I know you said that you thought this could be padded out to make a feature but I still think you are going to fall short at only 51 pages.
Sorry it wasn't more positive. Hopefully someone that appreciates westerns will give it a read, or you could always do a feature exchange with someone.
Best of luck with it.