I decided to use the Leatherwood scope mount for my M1A since I like the "adjustability" that they incorporate into their design. As I reported earlier, the supplied Chinese hardware is junk and should be replaced with quality US-made Allen screws. The actual parts & pieces of the scope mount are nicely made – so a $2 investment in screws can make this a truly outstanding mount.
The Leatherwood is advertised as permitting use of the iron sights – but mine is only barely so as the groove in the center of the rail needs to be a touch deeper. Cranking the rear sight up to 850 yards makes it work well – but you’ll need to decide how much to “hold under” to make hits with the irons..
My M1A has a crookedly drilled & threaded scope mount bolt-hole but I didn’t want to send the rifle back and have any of my other USGI parts somehow get swapped out especially since my trigger pack is a nicely done H&R that is the best trigger on any semi-auto that I own. Also, I’ve finally got the rifle tuned (and have found handloads) for accuracy, and do not wish to start all over again. So, I used a “compliance” style washer and was (seemingly) able to securely attach the mount.
What really worked well with the Leatherwood mount was the windage adjustment that is built-in to the rear of the scope mount. Leaving the scope mechanically centered, you pop a laser into the bore and simply look through the scope while using the “push-pull” screws on the back of the mount to center it. Afterwards, you remove the scope and tighten everything down and re-mount the scope and check windage again.
Now I need to get the M1A out and get it sighted in and do another range report. My eyesight is falling off (I’m 46), so I can no longer shoot well enough to get the expected accuracy from the rifle using the irons.