The last part of 9.3's post is a great suggestion.

When I build a hunting rifle for someone, I like to get my customers to try different rear-sight positions to see what distance best suits their eye. I use a sight dummy of black card and tape it to the barrel. Then I get them to mount the rifle and quickly sight on an object about 30 odd yards off, and move the “sight” as necessary to where the customer has their best sight picture. That distance from the end of the butt plus an inch is where the sight is then positioned, in just right place for that individual.

I have generally found that people over 45 need the rear sight some-where around 24 to 26 inches from the end of the butt, and those younger can usually accommodate anything up to about 4 inches less. Something to do with younger eyes being able to focus better and quicker than us older folk

Regards

Alex

alexbeer.com