My sole current M1A is a 2005 "Loaded" model in walnut. It is now past the 5000-round mark (having gone through a case of 5000 CCI#34 primers) and its reliability has been flawless.
I started the new rifle out with 500 rounds of 168 Matchkings for break-in, and since then the rifle has fired mostly a wildly-varied diet of CAST bullets. It functions with loads which it really has no right to make work, and with accuracy which sometimes amazes me. How about TEN 180-grain cast bullets in 0.60" from fifty yards, iron sights? Or, five consecutive cast-bullet hits on a 14"x16" plate, unsupported sitting position, no sling, iron sights....from 415 yards???
It works with cast bullets from 130 to 220 grains, from 1200 fps up to 2200 fps, and with accuracy from "great" to "astonishing" (not with all loads, of course, but with plenty of them).
Of course, it also does very well with the "regular" Matchking 168s, but I'm a cast-bullet man and that's mostly what I shoot....for about ten cents per round!
I truly love this rifle, and it has had ZERO modifications of any sort since it came out the the box. Unpacked, cleaned, and fired...and fired, and fired, up to as many as 600 rounds without cleaning, and STILL functioning.
Reliable? As reliable as the sun rising in the east.