A buddy recommended this mount to me as I have a decent 4-12x scope that's been laying around, and a flattop that's only seen a carry handle. Will this mount directly to the upper reciever?

Not that I'm going to be doing some force recon sniping, but do these hold a reasonable zero after removing/reinstalling?

They hold zero OK.  I had one mounted and it did fine.  The only problem with these is eye relief.  The scope eye lens will likely extend past the rear of the receiver.  You may have to adjust your cheek weld to compensate for the eye relief.  I am a nose-to-charging handle type of guy and it is hard for me to shoot any other way.

I have mine with a compact 1.5-4.5x scope and I can get it far enough forward to maintain my usual shooting position, but mongo001 is right in that eye relief may be a problem with some bigger scopes.

I agree with your buddy.  If you've got the scope laying around, MIGHT wanna put a scope on your upper, don't really wanna spend a lot of money, then this is THE way to go.  If you get more serious about mounts later, then you're only in it $40, and you could sell it for $30.

I've got one, and it's a perfect fit for me.  But then, I'm not a N2CH guy like Mongo.

Using a Burris Fullfield II with 3.1" - 3.8" eye relief, I actually turned the mount around backward (with the extended portion facing rear) because I needed it to clear my BUIS rather than be forward over the receiver.  I've seen a lot of guys with Simmons AETEC's mounted this same way.

I think that if you never take it off, it'll hold zero perfectly.  If you remove it and reinstall it using the "hand tight then quarter turn" method, you should still return pretty much zeroed.  (Mine does).

I really like it, and highly recommend it to people on a budget who still want a good mount.  It mounts directly to the flat-top, without any risers, extentions, extra pieces, etc. AND it's the same height as your irons (unlike the Armalite mount).  Don't pay more than $40 for it though.  I bought mine from ADCO.

Too bad they don't make a 30mm version.

Another cool thing you can do with it (if you need your optic farther forward).... If you use the inexpensive Yankee Hill FFT with rails, modular or otherwise, you can extend the mount forward onto the first couple slots of the forend.  this joins the upper to the forend, keeping them perfectly aligned and the tube CAN'T rotate... plus you get that extra eye relief, and a free-floated barrel to boot.

Thanks for the replies fellas. I went ahead and ordered from ADCO. This setup will just be used for fooling around at the range, 200 yards or less. It's a fairly large scope, but I'm not really a nose to CH guy. I think it'll be fine for my purposes.