Re: M1As
I built a match prepped M1A more or less as an experiment to see how accurate one can get the platform.
Answer is very, but its going to cost more than a nice AR10, be a royal pain in the arse to scope, and you're going to spend more time and $ keeping it up than anything else. Spare parts are expensive, and you have to be careful - as a large number are no good. (Rewelded Demil parts, used past replacement, or fakes.)
If you still want one, you need a good barrel - Krieger or Rock, or if you can track down one of the elusive Obermeyer M14 barrels use it. Get it put on by a good M14 Smith. Have them unitize the gas system as well. For stocks, while a lot of folks use the EBR/JAE platforms with a lot of success, they're expensive and won't let you use the heavy profiled match barrels. The alternative is to get it bedded into a McMillan, which wont be cheap either. (I went the McMillan route)
Add in a set of lapped and fitted NM/2A Iron sights, a NM reamed FH, a new gas plug, NM Op rod spring guide, and a good trigger job on the FCG, and you're ready for the most frustrating part of the precision M14. Scoping it.
Short answer: Sadlak.
Long answer: Sadlak custom fitted.
I had issues with an SEI, and an Arms #18 before I went to the Sadlak. While it worked fine, by this time, I was rather fed up with it and sold it. (The upkeep was time consuming, cleaning ti was a pain, and keeping it greased without removing it from the stock was. . . interesting.)
Total investment was well north of $3k, and almost 2 years. While it shot like it had eyes, I just didn't want to get another parts supply and mag stash built up to support it.
Some pics:
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Prone - with sling/Irons. Pulled Shot 2 cause my finger went numb (it was 20 degrees out. . . )
Would I do it again? Maybe. Would I pick the M14 over a precision AR10? No. The AR10 is easier to work on, cheaper to build, maintain, and upgrade. And the AR10 is a lot easier to scope. . . .