Quoted:
Get a fixed chopped A2 or something for rear sight
folding sights have a spring, and if this rifle is supposed to run 30 years without possibility of replacement parts, springs are bad
LOL... A2 sights have springs also.
Gee whiz.
EDIT
OK, I wont be such a smartass here... I just wish folks would know what they are talking about.
THe ball bearing in the elevation drum are backed up via springs. The aperture is held tight via a leaf spring.
In the worst case scenario, spikes wont be around to mail you new parts. A basic colt M4 will serve you needs.
After the armies fall, there will be LOTS of m4's etc just lying on the ground. You might want to use some of those parts.
Dont worry about a nice light trigger pull. Learn how to effectively use the basic M4 or M16 format as it is.
All it takes is a desire, and practice.