Joe, nice read!  I am a bit surprised that you didn't mention about greasing the bolt roller bearing.  There is a small special tool that helps to force the grease into the bearing as opposed to just applying it to the exterior.  It is very important that the bearing is PROPERLY lubed otherwise it will actually hurt the performance more than helping it.  An improperly or ungreased bearing can and will rust internally and can seize up.  I love me a good M1A but caution must be observed when shooting match ammo or reloaded ammo with benchrest primers as the (heavy) floating firing pin is notorious for causing slam-fires.

If you don't want to buy the special tool to grease the roller (or if you lose it) you can create your own easily enough. I used a 40 S&W case expanded somewhat with my 45 expander to slip tightly over the roller, packed the case with grease, and it worked great. Other pistol brass is probably better suited to this; a 41 or 44 case may work as is, but I'm not at home to check so I'm not sure.

I've heard from many sources that the Springfield M1A's cast receiver is slightly out of spec when it comes to installing a GI or GI spec scope mount.  If you want a great FORGED receiver that is completely spec then find a Polytech.  They were extremely popular for custom builds solely for the receiver and at one time the complete rifle was the same price or even cheaper than an aftermarket US made forged receiver.  Some say that the bolts weren't properly heat treated but others have thousands of rounds through their Polys with no headspace issues.

As mentioned, Springfield Armory, Inc. M1As use a cast receiver, but the newer ones also use cast parts.

Using cast parts on a USGI M14 would downgrade the M14.

I was gonna start another post but I think this may be the best place...

Has anyone seen a custom M1A with a Picatinny rail atop of the receiver instead of Irons?

I knew I saw one once, but for the life of me I haven't been able to get a hold of the company again, those where the same that where offering custom M1As in .243 Win.

Any luck?

Hm, no I don't think so, the one I saw completely removed the rear sight housing and instead there was a milled rail built into the receiver.

Or maybe I'm hallucinating.

...and where & how much can one get one of those tools for?

...that's a little too rich for for me for what it is.

Can they be found for less?

Yes they can!

$195
http://www.athenswater.com/EBR_KIT.html

$170.00

None that I know of.

Is there a polymer mag on the level of a MagPul P-Mag, for the M1A?

There isn't.

That is one solid looking rifle.   

Zero, I happen to have a spare Springfield Scout if you are interested...

So... I kinda bid on one on Gunbroker.
It's a low bid and I probably won't win but now I've convinced myself I can't live without one. 
So one way or another I'm gonna have one sooner rather than later.

Did you bid on this one?

That is one solid looking rifle.   

Thanks! ... there is much more to see on my new facebook page: H2O MAN's addiction to M14s