"...without altering the sight system..." Change your POA. As in aim higher. No 6 o'clock hold. Hold right on. And look through the rear sight at the front.
Otherwise, change the front sight(no files are required). Isn't terribly hard to do if you have a few tools, starting with a padded vise. You'll need a plastic mallet and a brass punch too.
Page 73 in this manual tells you exactly how to do it. Note the need for the provided UN & PW. You can adjust the size. I think it's a scanned copy of a book.
http://www.biggerhammer.net/manuals/pdfs/m1_carbine.pdf
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