What's wrong with a L.E.R. (Handgun / scout ) scope?
They come in variable power zoom models.
Here's a review of one 3X - 12X Burris pistol scope on a Ruger Charger.
The gun shot sub- M.O.A. groups with it.
http://gunsumerreports.com/review_burris_3-12x32_handgun_scope.php
The eye relief was at least ten inches, even at the maximum magnification.
I've used plenty of LER scopes, mostly on handguns (including rifle caliber handguns), but also on a lever action. For those applications, I liked it.
For a rifle in a more capable caliber, I've got issues with an LER scope that would keep ME from using it for me PERSONALLY. If it works for you, press on.
1. Very small FOV
2. Poor light transmission, resulting in a dark sight picture. Not good for early in the morning/late at night.
3. Overall poor quality picture when compared to a comparably priced/powered "standard" riflescope.
I'm not advising folks not to do it, it's just something I would not do. From a marketing standpoint, a .50BMG that you could only use a LER scope on would be a marketing disaster. Too many folks wanna shoot too far with a .50 to be saddled with a LER scope.